Primality Certificate for (4447^2347-1)/4446

Andy Steward8,559 digits19 December 2007
Originally by A.A.D.Steward 2007

This certificate uses a theorem of Brillhart, Lehmer and Selfridge 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 37.920000% factorization of N-1:

From Factorisation
44474447
Φ22 · 2 · 2 · 2 · 2 · 139
Φ33 · 7 · 79 · 11923
Φ619771363
Φ175347730534588963 · p43
Φ23461 · 599 · 2347 · 852427 · p66
Φ34137 · 3266763403483 · p44
Φ4647 · 35053 · 7306687 · 63875903126499829 · 76085536378456177 · p34
Φ51103 · 307 · 10619348211994273 · 867361678614031408770393753529 · p67
Φ699769159 · 410971705369 · c142
Φ102152287 · 910221648607 · 164903326793683 · 519099787721392552849244775742177122793 · p47
Φ138117991 · 517716460739413291 · c138
Φ3913561413257243573 · 13152164710878887 · c1253
Φ7827039 · 121993 · 192373 · 7652852156029 · 420363157117168967437 · c1237
Φ1173299790649 · 1631760314981557 · c2545
Φ23468886649 · 9691327 · 2497042408676043409 · p2536

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

806518 4189756327 8650236005 5441437059 3287652517 5979243697 8792557920 2847769641 8287783252 0821520561 3651596563 8174777062 9860375681 3778962123 4254686794 5978170014 3934149350 8506092356 8935048964 1931789684 4048242002 4984080777 1039162968 0263135542 3652317024 9377097257 2560713960 2995625359 5381022483 8763806746 8085446746 7900535319 5025688541 2466679027 7043724736 8320482055 3891930788 4368069732 9930034778 0973560089 5990919703 9284863994 1896980217 4838985757 0259654085 1983166868 8565287674 8933652543 2147568696 5418389524 8972003257 1511311944 1089469664 2353516685 4161091905 8971914633 7135173588 3640323517 3386940230 8891933197 8321964952 6009942771 1586275049 1707802685 7236547692 1409275834 7250249551 5385401954 8904457457 4442310393 4929515465 0347839499 2833198775 2565461738 2702910801 1965459857 7311222174 3558180569 6762605022 6009627656 2650274383 9138513008 2946331912 6695778189 9721834764 5980983125 3326389415 6679067551 0941028517 8879932909 0649540924 4033765162 0671986430 8352385480 1003215566 6945701030 8849278590 3403250354 5959997118 6329448900 5182148907 8700343876 7324717465 9438719622 7282531125 0380630553 2582863442 4411054016 3869449142 9401741043 5295248228 9422038554 6134240336 0811687220 7551538124 5063880230 7262995517 1353391650 3969558562 7928098693 7315666209 7842101982 3568674101 5791838809 8360030467 1282786774 3845665215 3133959145 3932607755 4877198229 8158857005 4425475708 2409177492 3089909579 2367152482 2990359104 4946405496 1372750256 3957275656 1271334807 3054177570 7455964279 5883695190 0455915937 6551560787 9577248137 3263410742 7228789562 3278125908 6059946622 1597983618 9483528972 9979387353 7196240363 4738999512 6601529671 8104908218 3046870525 1400276076 3119063612 7217824881 6962586023 3695505766 9555330070 0021565520 7347549420 6159350020 1496652213 5898748812 4012350233 0562734362 2736837623 6010009144 5275599699 0222908824 7582682981 0442867670 5028630452 1324964195 1511782374 1381109219 9460336650 7076347509 4942387130 3793039956 1639217106 8439238045 4709365118 2524112782 0803927675 9421502497 5819520661 1271033984 1873089039 5916389067 4061277109 8331440696 4644496389 4718883424 4093560950 5356492186 2307075404 1514939026 7124755934 7172137718 3281924757 2847385273 7834602229 7068487643 2769864514 3649483968 2909518183 8817555710 3364794704 9232246163 5382346485 2753867394 3802540381 8676533997 4825511923 9869640702 0386652698 4249245185 1963074138 5341519667 5354971495 2922757347 0571519967 5311419581 2168656163 2133782699 2682433010 3136206820 8958753257 9209067789 3687375067 1741755419 0959078593 4200792614 3077757359 4773321057 3571276350 5777624745 9031486991 8224156906 8905724217 1808303191 2055144804 5578567845 0522475037 6096886752 2424133039 5378363719 2586111623
1878351 1235827181 3504020092 3965317549 6450658325 2744072969 4695164693
327549 1557348106 3584275805 5991376489 8545080589 7557204181 8805555227
4612703 4110346250 5904240984 8713543610 9798278371
5225 6241871411 6069146326 9873136375 1062717611
437 5243483924 0571916915 5674499043 9211066507
519099787 7213925528 4924477574 2177122793
3091 6938646742 2682441266 1256645383

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) = 33.568608%

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 = 5 suffices.

Given such a witness, Pocklington's Theorem shows that every prime factor of N ≡ 1 (mod F). As F2>N, N can have no more than two prime factors.

Express N in base F

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

Brillhart, Lehmer and Selfridge

Brillhart, Lehmer and Selfridge's Theorem shows that N is prime if and only if c12-4·c2 is not a square (given 2F3 > N).

Here, c12-4·c2 is ≡ 27 (mod 63) and therefore cannot be a square and N is prime.