Primality Certificate for (4850^2017-1)/4849

Andy Steward7,431 digits18 November 2001
Originally by David Broadhurst, Bouk de Water & Sean Irvine 2001

This certificate uses a theorem of Konyagin and Pomerance to prove an integer N prime by making use of a partial prime factorization of N-1.

Factorizing N-1

As N is a Generalized Repunit, we make use of the algebraic factorization of N-1 to arrive at the following 31.179639% factorization of N-1:

From Factorisation
48502 · 5 · 5 · 97
Φ23 · 3 · 7 · 7 · 11
Φ3499 · 47149
Φ423522501
Φ63 · 271 · 28927
Φ729 · 29 · 29 · 10459 · 5526109 · 9234989
Φ8241 · 2295883843361
Φ919 · 73 · 1201483 · 7810095426481
Φ123217 · 171995021053
Φ147 · 4691 · 537502421 · 737253763
Φ1617 · 66337 · 914897 · 27909169 · 10631879633
Φ183 · 37 · 127 · 163 · 163 · 2341 · 33391 · 444547
Φ219123619 · 17969053074752347 · 1033044372744823225207
Φ24p30
Φ28421 · 19841053 · p35
Φ325857 · 103969 · p51
Φ36109 · 15589922869 · 42419718829 · 2349971597095529671189
Φ4243 · 289297 · 2714978281 · 5016625182530973078407386201
Φ481094209 · 59736840433 · p43
Φ56113 · 281 · 259262921 · 8484151531234479622066157929 · p48
Φ63254647 · 2323947403 · 237016072292168944279 · 10149665097726152154421561091857884478028983 · p55
Φ7281618727353409 · 2160282539608917481 · p57
Φ845959177748670891061983373 · p64
Φ96193 · 9601 · 19005701232899323088189509057 · p84
Φ112449 · p175
Φ126379 · 89925697 · 53569333567 · 551917517509 · 35599377876104888925031 · 88690601970624301873392897637867 · p46
Φ1442574721 · 28288563697 · 993178891729 · c149
Φ168673 · 49057 · 54601 · 226168154979418513 · p148
Φ224334583201 · 652733089 · p337
Φ252826905874777460113073255995717 · p236
Φ2882593 · c351
Φ336337 · 2689 · 11059827409 · 101239975622979697951226096689 · c309
Φ5043529 · 25509312922956409 · 55067630902381441 · c495
Φ672110881 · 116257 · 175393 · 38902753 · 1545112801 · c676
Φ10081009 · 32257 · 500977 · 17746388353 · c1039
Φ20162017 · 846641026386702300097 · c2099

From this partial factorization, we use sufficient of the largest prime factors of N-1 so that their product F is at least N 3/10 :

3104324 7331717618 2697919815 7797677903 4005574947 4927517782 5826066115 1020144574 2755589972 3145431217 4695943686 6597880184 3599782813 4314938198 7404977038 5922661675 6887152077 6614732124 6765038769 5396428958 8574576897 4162029166 9381512261 9285237990 2353343180 9174723425 8557253060 0208784890 1551871145 1386793430 0095004143 1619099158 3680110170 6313731009
285725 5661793187 7397052918 6084510381 2829470064 1068423569 2721681930 0466347721 4102609427 9883118704 3319628411 2714411126 0925771818 2104594610 5853353036 7115324754 9923334833 9367565051 6164047902 7080439036 7827896344 1465139944 9078826234 1070031053
18338 2171850697 0199363922 7587002410 2675151183 5376054436 3695122961 6485018145 7965323316 0260096051 5287268597 1781935380 2124233291 5318772677 6215263205 5994398688 8446748320 9214922049
20195534 4457629167 7383130002 5423156291 9086374832 6434295291 3247856371 8685509460 0910515809 1112338862 1675761254 9343682776 6475158541 9994162124 3283308857
2494 4681242279 8215770800 7186014500 3160110966 1204451777 4714056073 5767192186 6185702401
4815 2119186387 4668657524 9595029438 8349618220 5274556091 3068574937
1627426 3828960244 8249315849 2923474970 0515746885 4417977369
34143 5144440846 1056283581 9765044996 3394083522 9817041373
1 5391775731 2113098117 4420050997 2488151335 6775012097
41083566 3737967655 4184677554 9950842553 4918499513
152780 9246041996 3761760769 1616019251 1207968117
1014 9665097726 1521544215 6109185788 4478028983
143 3921203162 4463830400 7802161168 4669210833
20279 3500454931 5602908251 1014574877
88 6906019706 2430187339 2897637867
8269058747 7746011307 3255995717
3061497497 8034948575 4493750001
1012399756 2297969795 1226096689
190057012 3289932308 8189509057
84841515 3123447962 2066157929
50166251 8253097307 8407386201
59591 7774867089 1061983373
355 9937787610 4888925031
23 4997159709 5529671189
10 3304437274 4823225207
8 4664102638 6702300097
2 3701607229 2168944279
216028253 9608917481
22616815 4979418513
5506763 0902381441
2550931 2922956409
1796905 3074752347
8161 8727353409
781 0095426481
229 5883843361
99 3178891729
55 1917517509
17 1995021053
5 9736840433
5 3569333567
4 2419718829
2 8288563697
1 7746388353
1 5589922869
1 1059827409
1 0631879633
2714978281
2323947403
1545112801
737253763
652733089
537502421
334583201
259262921
89925697
38902753
27909169
23522501
19841053
9234989
9123619
5526109
2574721
1201483
1094209
914897
500977
444547
289297
254647
175393
116257
110881
103969
66337
54601
49057
47149
33391
32257
28927
10459
9601
5857
4691
3529
3217
2689
2593
2341
2017
1009
673
499
449
421
379
337
281
271
241
193
1632
127
113
109
97
73
43
37
293
19
17
11
73
52
34
2

Note that all prime factors listed above have been proven. As primes of under 250 decimal digits can be verified in a few seconds, proof of their primality is not included here, in order to save space. Larger prime factors can take from hours to months to prove; certificates for all such factors have been PKZIPped into this file.

We set R = (N-1)/F. Note that GCD(F,R)=1 and Log(F)/Log(N) = 31.179639%

Finding a Witness to Primality

Next, we find an integer witness w such that for each prime factor p of N-1, w(N-1) ≡ 1 mod N and GCD(w(N-1)/p-1,N) = 1. In this case, w = 7 suffices.

Express N in base F

As F3 < N < F4 and N ≡ 1 (mod F), we can let N = c3·F3 + c2·F2 + c1·F + 1. Let c4 = c3·F+c2.

Square Checks

For t = 0 to 5, we prove that Q(t) = (c1+t·F)2+4·t-4·c4 is not a perfect square. This is done by checking whether Q(t) is a quadratic residue modulo a variety of bases. If it happens to be a QR in all of the bases, we calculate s = floor(sqrt(Q(t))) and show that s2 < Q(t).

Continued Fraction

We approximate c1/F by a continued fraction u/v such that v is maximal while remaining less than F2 / N1/2 = 224169703 5814775443 7198102487 2985425007 5612323125 0508262096 7516807405 1919287688 5443635260 8378198316 2814127268 2836740630 8187484995 7740653065 5097118374 3399566542 3898774229 2241154062 1136094110 0630236905 3813936424 6986665345 3910135368 3398228996 2562374213 5915568631 8241429176 3477930184 3076950246 5786154425 3387885262 8716590692 9413386501 3143208091 4621594855 0726139317 4379613951 8405021436 8665572705 3782188956 8291146670 6680638597 7629540102 2549844306 3372058140 6053767637 1405065946 1117974533 0491969482 7117482761 7659390562 8528964348 2735210050 6181682254 1860039189 7552308729 3253999404 0149622594 9171536988 5699282527 0104745268 4133496583 7888020728 0781597527 2857736475 4990854974 5801817215 1341444669 4359162900 6507640955 2327754818 8504952989 8046716585 7382921130 0551167736 6595348837 8845814293 3788252060 6014350945 0274459863 3834830216 8139410865 2096024664 4864160989 3632589146 9021010499 2670865512 9575864585 5105366356 4776938284 8889110998 2821228621.

With those constraints, the unique continued fraction is: {0, 6, 1, 6, 1, 2, 1, 4, 1, 15, 1, 1, 1, 4, 2, 1, 2, 6, 5, 6, 4, 1, 9, 39, 1, 1, 6, 11, 8, 2, 1, 1, 7, 2, 1, 7, 2, 1, 1, 44, 1, 1, 5, 2, 73, 1, 13, 2, 1, 3, 3, 20, 1, 1, 2, 7, 3, 1, 1, 1, 1, 1, 86, 2, 1, 1, 1, 2, 1, 1, 1, 1, 5, 1, 8, 4, 3, 3, 2, 3, 6, 2, 3, 1, 13, 1, 16, 3, 7, 1, 3, 7, 1, 3, 1, 12, 8, 1, 1, 1, 1, 1, 1, 23, 1, 7, 1, 3, 1, 3, 7, 1, 1, 2, 2, 41, 2, 2, 3, 1, 29, 1, 1, 1, 1, 2, 4, 1, 1, 1, 1, 1, 2, 261, 2, 1, 14, 9, 2, 3, 1, 5, 5, 5, 2, 5, 2, 2, 11, 3, 2, 3, 1, 2, 1, 2, 1, 1, 3, 9, 2, 1, 2, 1, 1, 1, 2, 4, 1, 14, 2, 3, 4, 1, 3, 8, 1, 8, 1, 2, 1, 2, 1, 1, 7, 4, 1, 6, 1, 7, 3, 1, 1, 2, 2, 2, 1, 1, 6, 1, 4, 2, 1, 10, 1, 1, 1, 8, 5, 4, 2, 43, 18, 1, 3, 2, 1, 3, 1, 3, 6, 8, 1, 42, 1, 4, 2, 1, 2, 2, 1, 2, 2, 4, 3, 1, 2, 2, 5, 13, 8, 1, 20, 1, 2, 1, 1, 15, 1, 2, 2, 1, 7, 19, 166, 1, 138, 1, 1, 1, 1, 4, 7, 1, 3, 1, 5, 75, 2, 1, 4, 1, 4, 1, 3, 5, 2, 1, 80, 2, 1, 2, 2, 2, 3, 1, 3, 1, 6, 2, 2, 2, 2, 3, 2, 4, 12, 1, 43, 1, 5, 1, 1, 5, 1, 7, 1, 2, 4, 8, 2, 2, 1, 1, 1, 10, 8, 1, 19, 1, 14, 1, 1, 1, 2, 1, 102, 5, 5, 3, 13, 4, 1, 2, 75, 2, 14, 1, 1, 1, 6, 2, 1, 30, 1, 6, 1, 1, 1, 1, 2, 1, 1, 1, 14, 3, 9, 1, 2, 1, 3, 2, 3, 7, 1, 1, 1, 7, 1, 1, 5, 2, 15, 12, 2, 2, 1, 31, 189, 2, 12, 2, 1, 4, 1, 7, 1, 1, 1, 20, 3, 2, 31, 2, 1, 1, 2, 1, 3, 1, 2, 1, 1, 1, 1, 7, 3, 3, 1, 5, 7, 2, 1, 3, 2, 2, 1, 32, 2, 1, 1, 5, 1, 5, 1, 5, 1, 4, 1, 1, 9, 2, 93, 2, 1, 1, 1, 1, 1, 1, 6, 5, 2, 2, 6, 43, 1, 2, 15, 1, 1, 1, 6, 4, 1, 157, 1, 6, 1, 1, 1, 1, 2, 3, 1, 6, 1, 1, 1, 1, 6, 3, 1, 1, 6, 137, 1, 1, 2, 1, 1, 16, 1, 1, 1, 3, 6, 2, 5, 1, 1, 7, 1, 1, 17, 22, 2, 44, 2, 1, 1, 1, 2, 6, 4, 1, 5, 1, 23, 1, 6, 1, 13, 2, 1, 1, 2, 2, 1, 4, 1, 1, 7, 2, 3, 1, 1, 3, 5, 4, 1, 19, 1, 1, 7, 4, 1, 1, 38, 1, 28, 2, 1, 1, 7, 1, 1, 6, 3, 11, 2, 1, 2, 1, 4, 1, 2, 8, 1, 1, 3, 2, 3, 2, 1, 1, 3, 1, 3, 1, 12, 4, 30, 1, 1, 3, 1, 21, 3, 7, 3, 59, 23, 56, 1, 2, 16, 9, 2, 9, 97, 1, 1, 1, 20, 1, 1, 2, 16, 1, 3, 1, 3, 55, 1, 126, 3, 1, 1, 1, 389, 11, 1, 9, 1, 2, 1, 3, 1, 2, 1, 7, 1, 1, 1, 5, 1, 1, 13, 5, 2, 1, 1, 58, 2, 1, 1, 1, 9, 1, 1, 22, 1, 3, 1, 1, 7, 2, 2, 1, 1, 20, 1, 2, 17, 2, 3, 7, 1, 1, 14, 4, 12, 9, 5, 1, 37, 3, 8, 1, 1, 4, 6, 1, 1, 2, 1, 1, 16, 1, 8, 3, 3, 5, 1, 3, 1, 1, 1, 2, 1, 7, 3, 2, 18, 2, 1, 1, 3, 1, 116, 1, 4, 1, 1, 1, 1, 16, 1, 5, 1, 6, 1, 2, 2, 3, 1, 2, 1, 1, 1, 13, 1, 3, 1, 1, 7, 1, 2, 1, 3, 3, 4, 2, 1, 3, 3, 1, 23, 1, 1, 8, 8, 1, 1, 17, 4, 4, 1, 2, 1, 1, 2, 13, 6, 12, 1, 2, 2, 1, 6, 3, 1, 5, 3, 1, 4, 2, 1, 1, 1, 2, 1, 12, 2, 4, 6, 4, 2, 1, 1, 1, 1, 5, 4, 4, 2, 1, 1, 1, 12, 1, 2, 1, 2, 10, 1, 1, 13, 1, 1, 2, 1, 1, 1, 1, 5, 4, 4, 1, 2, 4, 5, 1, 6, 1, 1, 1, 3, 12, 2, 4, 1, 1, 4, 8, 5, 1, 1, 16, 10, 1, 4, 7, 1, 1, 2, 3, 3, 2, 1, 3, 1, 20, 1, 17, 1, 2, 1, 9, 13, 1, 9, 3, 4, 2, 16, 1, 41, 1, 4, 1, 8, 4, 1, 3, 1, 4, 27, 1, 2, 2, 4, 29, 2, 2, 1, 1, 4, 2, 1, 3, 2, 2, 8, 5, 5, 6, 1, 1, 4, 1, 125, 2, 1, 12, 1, 3, 1, 6, 1, 2, 1, 3, 1, 1, 1, 2, 5, 6, 11, 1, 6, 3, 1, 26, 1, 1, 1, 3, 18, 1, 1, 4, 3, 1, 3, 6, 1, 1, 1, 1, 317, 5, 6, 3, 2, 1, 5, 56, 5794, 10, 2, 2, 5, 1, 14, 2, 1, 1, 20, 2, 1, 5, 6, 1, 130, 1, 1, 2, 3, 2, 1, 1, 2, 7, 2, 1, 2, 4, 1, 1, 1, 1, 1, 2, 19, 1, 1, 1, 1, 22, 1, 1, 1, 2, 172, 2, 4, 2, 3, 4, 6, 2, 1, 2, 1, 2, 3, 2, 2, 5, 1, 1, 1, 3, 9, 2, 7, 1, 3, 2, 7, 1, 30, 2, 4, 1, 28, 1, 3, 11, 1, 1, 4, 1, 24, 2, 5, 1, 2, 1, 1, 3, 1, 1, 1, 2, 1, 929, 12, 1, 20, 1, 16, 13, 6, 53, 1, 1, 2, 4, 1, 41, 1, 3, 2, 1, 14, 4, 2, 2, 51, 10, 1, 2, 2, 12, 2, 4, 3, 7, 4, 1, 1, 1, 4, 1, 4, 1, 2, 2, 1, 2, 1, 1, 2, 1, 3562, 1, 1, 26, 3, 6, 2, 3, 9, 1, 1, 1, 30, 1, 25, 1, 1, 1, 1, 1, 1, 3, 1, 4, 1, 6, 2, 1, 3, 3, 1, 1, 4, 1, 18, 1, 1, 1, 2, 3, 1, 3, 8, 1, 2, 3, 2, 1, 15, 1, 7, 49, 6, 1, 1, 4, 1, 25, 4, 1, 5, 1, 30, 1, 1, 4, 11, 2, 6, 2, 1, 23, 11, 1, 4, 4, 1, 2, 2, 1, 17, 1, 1, 2, 1, 2, 4, 1, 4, 5, 5, 1, 3, 6, 1, 33, 1, 14, 2, 3, 1, 22, 3, 1, 3, 2, 1, 2, 2, 2, 3, 1, 2, 2, 1, 2, 1, 1, 1, 3, 3, 1, 6, 3, 1, 1, 6, 2, 1, 1, 1, 2, 1, 1, 1, 1, 6, 1, 5, 6, 1, 21, 1, 59, 1, 4, 2, 4, 1, 7, 2, 1, 28, 1, 3, 1, 4, 1, 3, 2, 1, 5, 6, 2, 8, 3, 6, 2, 1, 6, 2, 3, 1, 21, 1, 1, 35, 1, 1, 3, 1, 2, 4, 1, 10, 1, 8, 2, 4, 1, 1, 1, 2, 1, 5, 3, 1, 1, 1, 10, 1, 14, 2, 1, 1, 1, 2, 1, 2, 3, 5, 1, 11, 1, 1, 7, 3, 5, 9, 1, 4, 1, 5, 1, 3, 2, 1, 2, 10, 12, 1, 63, 3, 3, 1, 3, 43, 1, 2, 1, 1, 1, 16, 2, 1, 3, 49, 48, 1, 1, 1, 1, 4, 6, 2, 2, 1, 1, 7, 47, 1, 1, 1, 7, 4, 1, 18, 1, 5, 5, 3, 1, 1, 1, 2, 6, 1, 72, 10, 1, 6, 16, 5, 25, 2, 3, 8, 1, 1, 3, 1, 1, 3, 10, 22, 2, 4, 1, 2, 4, 1, 12, 2, 1, 1, 30, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 43, 2, 2, 1, 5, 1, 40, 2, 7, 5, 1, 1, 3, 1, 1, 1, 3, 1, 4, 1, 1, 10, 4, 7, 6, 1, 10, 2, 1, 2, 1, 2, 4, 12, 18, 1, 3, 1, 2, 5, 8, 2, 1, 1, 4, 1, 5, 2, 1, 4, 2, 6, 1, 4, 4, 6, 1, 3, 18, 3, 2, 2, 1, 8, 2, 1, 2, 1, 3, 1, 4, 4, 3, 1, 3, 1, 2, 6, 8, 3, 4, 32, 1, 1, 2, 1, 8, 1, 2, 1, 2, 2, 1, 1, 23, 33, 2, 5, 1, 1, 17, 2, 1, 1, 56, 1, 10, 5, 3, 3, 2, 5, 1, 4, 2, 20, 2, 2, 3, 5, 1, 1, 1, 13, 4, 3, 1, 15, 3, 1, 43, 2, 6, 6, 6, 3, 2, 18, 5, 1, 5, 1, 5, 1, 6, 1, 1, 14, 4, 2, 1, 2, 3, 1, 1, 3, 2, 34, 1, 5, 3, 2, 19, 1, 3, 2, 1, 1, 5, 1, 2, 8, 2, 1, 32, 3, 1, 4, 2, 2, 1, 1, 25, 1, 2, 4, 3, 1, 1, 1, 5, 20, 3, 2, 4, 1, 1, 2, 9, 3, 1, 3, 2, 1, 2, 1, 1, 1, 1, 3, 1, 10, 1, 2, 1, 2, 1, 1, 1, 8, 1, 1, 2, 2, 3, 1, 2, 1, 7, 1, 3, 1, 3, 1, 2, 3, 7, 1, 7, 1, 1, 3, 1, 2, 1, 2, 1, 1, 2, 1, 3, 1, 4, 1, 4, 1, 2, 2, 5, 3, 1, 1, 2, 2, 3, 2, 1, 1, 72, 3, 1, 2, 61, 1, 2, 2, 1, 1, 1, 2, 8, 1, 1, 12, 1, 2, 1, 1, 4, 1, 1, 1, 2, 3, 4, 1, 18, 1, 9, 3, 5, 8, 508, 1, 1, 2, 1, 4, 1, 1, 2, 2, 2, 2, 1, 9, 1, 39, 1, 3, 1, 2, 10, 7, 1, 2, 1, 1, 3, 33, 2, 26, 1, 2, 1, 1, 2, 1, 29, 1, 1, 4, 1, 1, 6, 7, 1, 71, 2, 8, 1, 2, 13, 1, 59, 15, 1, 1, 1, 2, 1, 7, 1, 1, 2, 5, 4, 13, 2, 1, 1, 1, 1, 4, 3, 2, 15, 2, 2, 1, 1, 13, 2, 1, 17, 5, 1, 16, 2, 1, 20, 1, 3, 8, 3, 1, 1, 2, 9, 1, 8, 1, 6, 24, 20, 7, 1, 2, 3, 1, 2, 1, 1, 1, 3, 6, 1, 47, 1, 3, 1, 2, 13, 39, 1, 1, 10, 1}, giving these values for u and v:

… as taking one more term in the continued fraction would give a value of v of 645891593 2452146053 4586773436 8481136638 8613546314 3208003214 9917141671 4375888654 6147140194 8766787169 7917190311 5219651452 1259636672 5138335828 8191809422 2298037797 9633623507 5241770120 0109522201 7446262036 7641470966 0831994954 8140051529 3940495954 4415376180 8656990658 0834903551 3937578454 4875478168 8870752049 3772950251 1109261368 6694345897 4114204795 1398350358 0648061316 6437567894 3093176681 4101273849 4282376726 2492654958 9418550038 9034103277 9740664131 4667497313 4562699159 9952746937 6904284309 2166365203 2297958413 1853161906 7711094300 5294795164 8544441468 2348317497 8479088390 1400874191 7147482546 2846590714 2562098337 4660195857 5006276140 0128382778 6077454297 0993790743 6406214168 0215106310 6371535144 0734607061 1038304540 2069014285 2689031315 4528608630 9458605726 0221690248 6623341120 6059380919 3028513475 3841998375 6294089453 6760982296 9973574043 5439203513 2202899078 0567575208 0520037181 8965217248 2652547590 2128069263 0891578403 3411646632 4551603575, which is too large.

We also need to calculate d = floor(c4·v/F + 0.5) = 160989693 0110041716 5255734763 7341409673 8745086880 3961310201 4883388576 1913411833 0797291685 4196906222 1249050125 5422721165 8138827422 9824179774 8351111147 3072387902 9589022733 7205502276 2651134685 3259392047 0226740639 3582623036 1280146308 2822570668 9327587369 9326156936 1391611919 7773663528 9075402391 5617834534 0075400057 7530389255 8149084091 3075154829 1395530380 5678518873 3366694821 9666860314 8224036061 5400660150 1754609825 8018661534 4123914182 2422673688 7413669935 7327359276 8306587029 8696122010 8767218701 4783923464 9685987634 7231055259 5181769039 6372948028 9407471231 0545494496 5845677563 2773318986 9945718818 6906707520 3194774508 1641847934 1362540710 9224142529 6295833772 6527260622 6465448171 6927311118 8224270037 2458277233 7163230704 4696740831 6838381975 5049577299 6249783050 0368615421 8561292096 2787765416 8985908428 4425331402 2524332178 1552407223 0345540544 3960391764 7105976965 7512313319 6201714779 6927316412 0361428454 9394317518 8731579975 0857369105 2571510444 9815322850 4342278188 5441373844 7081238294 6282405739 2243391722 3005443944 0025561573 3035147794 8674106279 3831085973 2992242699 5037707051 9511447805 0142738384 6630809006 3202025984 2773182605 1724531151 2716428892 1729501435 9783901506 9352086948 4325805409 6779750404 4982303305 4581618496 0995199044 2566006499 2416870815 2819318797 1912998403 8394915085 3381013674 3601238150 4163116090 3873980923 6394253776 4753042624 2365039618 0301700064 6510759991 6026933017 1497982622 0705223174 1232164249 3567346414

Cubic Polynomial

We now consider the cubic P(x)= v·x3 + (u·F-c1·v)·x2 + (c4·v-d·F+u)·x - d, which we express as: z1·x3 + z2·x2 + z3·x + z4, where:

We need to prove that this cubic has no integer roots r such that r·F+1 is a non-trivial factor of N. Clearly r (if it exists) must lie between 1 and R.

As z1 is > 0 and z4 is < 0, we know that P has at least one real root r1 > 0. This is easily found:

Note that the root is not an integer but actually lies in the interval (r1,r1+1).

To see if P has any more real roots, we examine the quadratic derivative P' of P = 3·z1·x2 + 2·z2·x + z3, which we express in the usual quadratic form as a·x2 + b·x + c

As b2-4·a·c is negative, P' has no real roots. Therefore, P has no turning points and is monotonic, implying that r1 is the only real root of P.

There are no integer roots of P in the interval (1,R), so the proof of primality is complete.