A000068 -id:A000068 - cp's OEIS frontend

A251597 Numbers b such that b^65536 + 1 is prime.

1, 48594, 108368, 141146, 189590, 255694, 291726, 292550, 357868, 440846, 544118, 549868, 671600, 843832, 857678, 1024390, 1057476, 1087540, 1266062, 1361846, 1374038, 1478036, 1483076, 1540550, 1828502, 1874512, 1927034, 1966374, 2019300, 2041898, 2056292

Offset: 1

Felix Fröhlich, Dec 05 2014

nonn

Base values b yielding a generalized Fermat prime b^(2^k) + 1 for k=16.

First square member of sequence is 3934049284 = (A253854(1))^2. - Jeppe Stig Nielsen, Jun 29 2015

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..4048 (some previous contributions from Ray Chandler and Felix Fröhlich)
C. K. Caldwell, The Prime Database, Search Output.
Y. Gallot, Generalized Fermat Prime Search
Merfighters, Table of known GF primes b^n+1 where n(exponent) is at least 8192, Mersenne Wiki
J. S. S. Nielsen, Generalized Fermat Primes sorted by base (see table at the bottom of the page)
PrimeGrid, GFN Status by n-Range, Message 89145

Cf. A056993, A005574, A000068, A006314, A006313, A006315, A006316, A056994, A056995, A057465, A057002, A088361, A088362, A226528, A226529, A226530, A253854, A244150, A243959, A321323.

Corrected last term, and extended, by Jeppe Stig Nielsen, Jun 29 2015
New b-file, updated with data from Message 89145 at PrimeGrid forum uploaded and sequence data corrected, by Felix Fröhlich, Jan 03 2016
a(1) = 1 inserted and new b-file by Jeppe Stig Nielsen, Sep 10 2018

A243959 Numbers k such that k^524288 + 1 is prime.

Original entry on oeis.org

1, 75898, 341112, 356926, 475856, 1880370, 2061748, 2312092, 2733014, 2788032, 2877652, 2985036, 3214654, 3638450, 4896418, 5897794, 6339004, 8630170, 9332124, 10913140, 11937916

Offset: 1

Felix Fröhlich, Jun 16 2014

Numbers k such that k^(2^j) + 1 is a generalized Fermat prime for j=19.
1880370 is a member, but its position is not yet known. - Jeppe Stig Nielsen, Jan 24 2018
PrimeGrid has now tested and double checked the necessary candidates to prove that 1880370 is a(6). - Jeppe Stig Nielsen, Feb 20 2018

C. Caldwell, The largest known primes (Primes with 600,000 or more digits)
H. Dubner and Y. Gallot, Distribution of generalized Fermat prime numbers, Math. Comp., 71 (2002), 825-832.
J. S. S. Nielsen, Generalized Fermat Primes sorted by base (See table at the bottom of the page.)
PrimeGrid, Announcement of n=75898
PrimeGrid, Announcement of n=341112
PrimeGrid, Announcement of n=356926
PrimeGrid, Announcement of n=475856
PrimeGrid, Announcement of n=1880370
PrimeGrid, Announcement of n=2061748
PrimeGrid, Announcement of n=2312092
PrimeGrid, GFN Prime Search Status and History
PrimeGrid, PrimeGrid Primes - (GFN524288) Generalized Fermat Prime Search n=524288
The Prime Pages, Database search results

Cf. A056993, A005574, A000068, A006314, A006313, A006315, A006316, A056994, A056995, A057465, A057002, A088361, A088362, A226528, A226529, A226530, A251597, A253854, A244150, A321323.

is(n)=isprime(n^524288+1) \\ Charles R Greathouse IV, Feb 20 2017

a(6) from Jeppe Stig Nielsen, Feb 20 2018
a(7) from Jeppe Stig Nielsen, Apr 27 2018
a(1) = 1 inserted and a(8) added by Jeppe Stig Nielsen, Sep 10 2018
a(9)-a(12) from Jeppe Stig Nielsen, Sep 21 2019
a(13) from Jeppe Stig Nielsen, Dec 27 2019
a(14) from Ray Chandler, Mar 28 2022
a(15)-a(17) communicated by Jeppe Stig Nielsen, Apr 01 2024
a(18)-a(21) from Jeppe Stig Nielsen, Jan 11 2025

A253854 Numbers b such that b^131072 + 1 is prime.

Original entry on oeis.org

1, 62722, 130816, 228188, 386892, 572186, 689186, 909548, 1063730, 1176694, 1361244, 1372930, 1560730, 1660830, 1717162, 1722230, 1766192, 1955556, 2194180, 2280466, 2639850, 3450080, 3615210, 3814944, 4085818, 4329134, 4893072, 4974408, 5326454, 5400728, 5471814

Offset: 1

Felix Fröhlich, Jan 17 2015

Base values b yielding a generalized Fermat prime b^(2^k)+1 for k=17.

The first member exceeding 10^((10^6-1)/2^17) is known to be 42654182. - Jeppe Stig Nielsen, Jan 30 2016

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..1243
C. K. Caldwell, 1560730^131072+1, The Largest Known Primes
C. K. Caldwell, Search result %^131072+1.
J. S. S. Nielsen, Generalized Fermat Primes sorted by base (see table at the bottom of the page)
PrimeGrid, PrimeGrid Primes - (GFN131072) Generalized Fermat Prime Search n=131072
PrimeGrid, Generalized Fermat statistics

Cf. A056993, A005574, A000068, A006314, A006313, A006315, A006316, A056994, A056995, A057465, A057002, A088361, A088362, A226528, A226529, A226530, A251597, A244150, A243959, A321323.

Missing term a(8) inserted by Jeppe Stig Nielsen, Jul 02 2015
a(13) from Felix Fröhlich, Nov 01 2015
a(14)-a(20) from Jeppe Stig Nielsen, Jan 30 2016
a(21)-a(31) from Jeppe Stig Nielsen, Sep 06 2017
a(1) = 1 inserted by Jeppe Stig Nielsen, Sep 10 2018

A321323 Numbers k such that k^(2^20) + 1 is prime (a generalized Fermat prime).

Original entry on oeis.org

1, 919444, 1059094, 1951734, 1963736, 3843236

Offset: 1

Jeppe Stig Nielsen, Nov 04 2018

Chris K. Caldwell, The Prime Database: 919444^1048576 + 1
Chris K. Caldwell, The Prime Database: 1059094^1048576 + 1
Chris K. Caldwell, The Prime Database: ?^1048576 + 1

Cf. A056993, A005574, A000068, A006314, A006313, A006315, A006316, A056994, A056995, A057465, A057002, A088361, A088362, A226528, A226529, A226530, A251597, A253854, A244150, A243959.

a(4) from Jeppe Stig Nielsen, Aug 31 2022
a(5) from Jeppe Stig Nielsen, Oct 21 2022
a(6) from Jeppe Stig Nielsen, Jan 11 2025

A096172 Largest prime factor of n^4 + 1.

Original entry on oeis.org

2, 17, 41, 257, 313, 1297, 1201, 241, 193, 137, 7321, 233, 14281, 937, 1489, 65537, 41761, 929, 3833, 160001, 97241, 3209, 139921, 331777, 11489, 26881, 6481, 614657, 353641, 3361, 1129, 61681, 6113, 1336337, 750313, 98801, 10529, 50857, 1156721

Offset: 1

Hugo Pfoertner, Jun 19 2004

nonn

Mabkhout shows that a(n) >= 137 for n > 3. - Charles R Greathouse IV, Apr 07 2014

			a(1)=2 because 1^4 + 1 = 2;
a(2)=17: 2^4 + 1 = 17;
a(8)=241: 8^4 + 1 = 4097 = 17*241.

Mustapha Mabkhout, Minoration de P(x^4+1), Rendiconti del Seminario della Facoltà di Scienze dell'Università di Cagliari 63:2 (1993), pp. 135-148.

Vincenzo Librandi and T. D. Noe, Table of n, a(n) for n = 1..10000 (first 1000 terms from Vincenzo Librandi)
Florian Luca, Primitive divisors of Lucas sequences and prime factors of x^2 + 1 and x^4 + 1, Acta Academiae Paedagogicae Agriensis, Sectio Mathematicae 31 (2004), pp. 19-24.
Marina Mureddu, A lower bound for P(x^4+1), Annales de la Faculté des sciences de Toulouse: Mathématiques, Serie 5, Vol. 8, No. 2 (1986-1987), pp. 109-119.

Cf. A000068, A002523, A014442, A037896, A006530, A069170, A096169, A096171.

FactorInteger[#^4+1][[-1,1]]&/@Range[40] (* Harvey P. Dale, Apr 30 2012 *)

a(n)=my(f=factor(n^4+1)[,1]); f[#f] \\ Charles R Greathouse IV, Apr 07 2014

a(n) = A006530(1+n^4) = A014442(n^2). - R. J. Mathar, Jan 28 2017
From Amiram Eldar, Oct 28 2024: (Start)
a(n) > 113 for n > 3 (Mureddu, 1986-1987).
a(n) >= 233 for n >= 11 (Luca, 2004). (End)

A246397 Numbers n such that Phi(12, n) is prime, where Phi is the cyclotomic polynomial.

Original entry on oeis.org

2, 3, 4, 5, 9, 10, 12, 13, 17, 25, 27, 30, 31, 36, 38, 39, 43, 48, 52, 55, 56, 61, 62, 65, 83, 92, 94, 99, 100, 104, 105, 109, 114, 118, 126, 131, 166, 168, 169, 172, 183, 185, 190, 194, 196, 198, 209, 224, 225, 229, 231, 239, 244, 257, 260, 261, 263, 269, 270, 272, 278, 291, 296, 299, 300, 302, 308, 311

Offset: 1

Eric Chen, Nov 13 2014

nonn

Numbers n such that n^4-n^2+1 is prime, or numbers n such that A060886(n) is prime.

G. C. Greubel, Table of n, a(n) for n = 1..10000

Cf. A008864 (1), A006093 (2), A002384 (3), A005574 (4), A049409 (5), A055494 (6), A100330 (7), A000068 (8), A153439 (9), A246392 (10), A162862 (11), this sequence (12), A217070 (13), A006314 (16), A217071 (17), A164989 (18), A217072 (19), A217073 (23), A153440 (27), A217074 (29), A217075 (31), A006313 (32), A097475 (36), A217076 (37), A217077 (41), A217078 (43), A217079 (47), A217080 (53), A217081 (59), A217082 (61), A006315 (64), A217083 (67), A217084 (71), A217085 (73), A217086 (79), A153441 (81), A217087 (83), A217088 (89), A217089 (97), A006316 (128), A153442 (243), A056994 (256), A056995 (512), A057465 (1024), A057002 (2048), A088361 (4096), A088362 (8192), A226528 (16384), A226529 (32768), A226530 (65536).

Cf. A060886, A125258, A085398, A124990.

A246397:=n->`if`(isprime(n^4-n^2+1),n,NULL): seq(A246397(n),n=1..300); # Wesley Ivan Hurt, Nov 14 2014

Select[Range[350], PrimeQ[Cyclotomic[12, #]] &] (* Vincenzo Librandi, Jan 17 2015 *)

for(n=1,10^3,if(isprime(polcyclo(12,n)),print1(n,", "))); \\ Joerg Arndt, Nov 13 2014

A096169 Odd n such that (n^4+1)/2 is prime.

Original entry on oeis.org

3, 5, 7, 11, 13, 17, 21, 23, 29, 35, 39, 57, 61, 65, 71, 73, 81, 103, 105, 113, 115, 119, 129, 153, 165, 169, 171, 199, 203, 205, 251, 259, 267, 275, 309, 313, 317, 333, 337, 339, 353, 363, 403, 405, 415, 419, 431, 445, 449, 453, 455, 463, 471, 477, 479, 487

Offset: 1

Hugo Pfoertner, Jun 19 2004

nonn

			a(1)=3 because (3^4+1)/2=82/2=41 is prime.

Zak Seidov, Table of n, a(n) for n = 1..1000

Cf. A000068 n^4+1 is prime, A037896 primes of the form n^4+1, A096170 primes of the form (n^4+1)/2, A096171 n^4+1 is an odd semiprime, A096172 largest prime factor of n^4+1.

[ n: n in [0..2500] | IsPrime((n^4+1) div 2) ]; // Vincenzo Librandi, Apr 15 2011

Select[Range[1,501,2],PrimeQ[(#^4+1)/2]&] (* Harvey P. Dale, Jun 04 2011 *)

A123599 Smallest generalized Fermat prime of the form a^(2^n) + 1, where base a>1 is an integer; or -1 if no such prime exists.

Original entry on oeis.org

3, 5, 17, 257, 65537, 185302018885184100000000000000000000000000000001

Offset: 0

Alexander Adamchuk, Nov 14 2006

nonn

First 5 terms {3, 5, 17, 257, 65537} = A019434 are the Fermat primes of the form 2^(2^n) + 1. Note that for all currently known a(n) up to n = 17 last digit is 7 or 1 (except a(0) = 3 and a(1) = 5). Corresponding least bases a>1 such that a^(2^n) + 1 is prime are listed in A056993.

The last-digit behavior clearly continues since, for any a, we have that a^(2^2) will be either 0 or 1 modulo 5. So for n >= 2, a(n) is 1 or 2 modulo 5, and odd. - Jeppe Stig Nielsen, Nov 16 2020

Charles R Greathouse IV, Table of n, a(n) for n = 0..9
Eric Weisstein's World of Mathematics, Generalized Fermat Number.

Cf. A000215, A019434, A056993.

Cf. A006093, A005574, A000068, A006314, A006313, A006315, A006316, A056994, A056995, A057465, A057002.

Do[f=Min[Select[ Table[ i^(2^n) + 1, {i, 2, 500} ],PrimeQ]];Print[{n,f}],{n,0,9}]

A250177 Numbers n such that Phi_21(n) is prime, where Phi is the cyclotomic polynomial.

Original entry on oeis.org

3, 6, 7, 12, 22, 27, 28, 35, 41, 59, 63, 69, 112, 127, 132, 133, 136, 140, 164, 166, 202, 215, 218, 276, 288, 307, 323, 334, 343, 377, 383, 433, 474, 479, 516, 519, 521, 532, 538, 549, 575, 586, 622, 647, 675, 680, 692, 733, 790, 815, 822, 902, 909, 911, 915, 952, 966, 1025, 1034, 1048, 1093

Offset: 1

Eric Chen, Dec 24 2014

nonn

G. C. Greubel, Table of n, a(n) for n = 1..10000

Cf. A008864 (1), A006093 (2), A002384 (3), A005574 (4), A049409 (5), A055494 (6), A100330 (7), A000068 (8), A153439 (9), A250392 (10), A162862 (11), A246397 (12), A217070 (13), A250174 (14), A250175 (15), A006314 (16), A217071 (17), A164989 (18), A217072 (19), A250176 (20), this sequence (21), A250178 (22), A217073 (23), A250179 (24), A250180 (25), A250181 (26), A153440 (27), A250182 (28), A217074 (29), A250183 (30), A217075 (31), A006313 (32), A250184 (33), A250185 (34), A250186 (35), A097475 (36), A217076 (37), A250187 (38), A250188 (39), A250189 (40), A217077 (41), A250190 (42), A217078 (43), A250191 (44), A250192 (45), A250193 (46), A217079 (47), A250194 (48), A250195 (49), A250196 (50), A217080 (53), A217081 (59), A217082 (61), A006315 (64), A217083 (67), A217084 (71), A217085 (73), A217086 (79), A153441 (81), A217087 (83), A217088 (89), A217089 (97), A006316 (128), A153442 (243), A056994 (256), A056995 (512), A057465 (1024), A057002 (2048), A088361 (4096), A088362 (8192), A226528 (16384), A226529 (32768), A226530 (65536), A251597 (131072), A244150 (524287), A243959 (1048576).

Cf. A085398 (Least k>1 such that Phi_n(k) is prime).

a250177[n_] := Select[Range[n], PrimeQ@Cyclotomic[21, #] &]; a250177[1100] (* Michael De Vlieger, Dec 25 2014 *)

{is(n)=isprime(polcyclo(21,n))};
for(n=1,100, if(is(n)==1, print1(n, ", "), 0)) \\ G. C. Greubel, Apr 14 2018

A070025 At these values of k, the 1st, 2nd, 3rd and 4th cyclotomic polynomials all give prime numbers.

Original entry on oeis.org

6, 150, 2730, 9000, 9240, 35280, 41760, 43050, 53280, 65520, 76650, 96180, 111030, 148200, 197370, 207480, 213360, 226380, 254280, 264600, 309480, 332160, 342450, 352740, 375450, 381990, 440550, 458790, 501030, 527070, 552030, 642360, 660810

Offset: 1

Labos Elemer, May 07 2002

Numbers k such that k-1, k+1, k^2+k+1 and k^2+1 are all primes.

			For k = 6: 5, 7, 43 and 37 are prime values of the first 4 cyclotomic polynomials.

Amiram Eldar, Table of n, a(n) for n = 1..10000

Cf. A070155, A070156, A070157, A000068, A006313, A006314, A006315, A006316, A056993, A056994, A056995, A005574, A057465, A057002, A070020, A070042.

lst={};Do[If[PrimeQ[n-1]&&PrimeQ[n+1]&&PrimeQ[1+n+n^2]&&PrimeQ[1+n^2], AppendTo[lst, n]], {n, 10^6}];lst (* Vladimir Joseph Stephan Orlovsky, Aug 19 2008 *)
Select[Range[10^6], Function[k, AllTrue[Cyclotomic[#, k] & /@ Range@ 4, PrimeQ]]] (* Michael De Vlieger, Jul 18 2017 *)

is(k) = isprime(k-1) && isprime(k+1) && isprime(k^2+1) && isprime(k^2+k+1); \\ Amiram Eldar, Sep 24 2024

cp's OEIS Frontend

A251597 Numbers b such that b^65536 + 1 is prime.

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A243959 Numbers k such that k^524288 + 1 is prime.

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A253854 Numbers b such that b^131072 + 1 is prime.

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A321323 Numbers k such that k^(2^20) + 1 is prime (a generalized Fermat prime).

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A096172 Largest prime factor of n^4 + 1.

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A246397 Numbers n such that Phi(12, n) is prime, where Phi is the cyclotomic polynomial.

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Maple

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A096169 Odd n such that (n^4+1)/2 is prime.

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Magma

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A123599 Smallest generalized Fermat prime of the form a^(2^n) + 1, where base a>1 is an integer; or -1 if no such prime exists.

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A250177 Numbers n such that Phi_21(n) is prime, where Phi is the cyclotomic polynomial.

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