A068481 -id:A068481 - cp's OEIS frontend

A068480 Numbers n such that gcd(n!-1,2^n+1)>1.

1, 29, 41, 53, 69, 105, 125, 141, 153, 165, 189, 233, 249, 273, 293, 321, 329, 405, 413, 429, 441, 453, 485, 581, 585, 629, 641, 653, 713, 729, 741, 761, 765, 809, 813, 849, 893, 905, 989, 993, 1005, 1013, 1041, 1049, 1089, 1121, 1125, 1133, 1169, 1205

Offset: 1

Benoit Cloitre, Mar 10 2002

nonn

G. C. Greubel, Table of n, a(n) for n = 1..1000

Cf. A000051 (2^n+1), A033312 (n!-1).

Cf. A068481, A068482, A068483.

Filtered([1..1230],n->Gcd(Factorial(n)-1,2^n+1)>1); # Muniru A Asiru, Oct 16 2018

select(n->gcd(factorial(n)-1,2^n+1)>1,[$1..1230]); # Muniru A Asiru, Oct 16 2018

Select[Range[2500], GCD[#! - 1, 2^# + 1] > 1 &] (* G. C. Greubel, Oct 15 2018 *)

isok(n) = gcd(n!-1, 2^n+1) > 1; \\ Michel Marcus, Oct 16 2018

A068483 Numbers n such that gcd(n!-1,2^n-1)>1.

Original entry on oeis.org

11, 15, 35, 75, 83, 111, 119, 135, 155, 179, 219, 231, 243, 323, 359, 375, 455, 459, 483, 491, 515, 519, 525, 531, 551, 611, 615, 639, 651, 663, 699, 719, 723, 735, 771, 779, 783, 803, 879, 915, 923, 939, 999, 1043, 1103, 1119, 1175, 1199, 1271, 1323

Offset: 1

Benoit Cloitre, Mar 10 2002

G. C. Greubel, Table of n, a(n) for n = 1..1000

Cf. A000225 (2^n-1), A033312 (n!-1).

Cf. A068480, A068481, A068482.

Select[Range[2500], GCD[#! - 1, 2^# - 1] > 1 &] (* G. C. Greubel, Oct 15 2018 *)

isok(n) = gcd(n!-1,2^n-1) > 1; \\ Michel Marcus, Oct 16 2018

A068482 Numbers n such that gcd(n!+1,2^n-1)>1.

Original entry on oeis.org

2, 3, 4, 6, 10, 12, 16, 18, 22, 23, 28, 30, 36, 39, 40, 42, 46, 51, 52, 58, 60, 63, 66, 70, 72, 78, 82, 88, 95, 96, 99, 100, 102, 106, 108, 112, 126, 130, 131, 135, 136, 138, 148, 150, 156, 162, 166, 172, 178, 180, 183, 190, 191, 192, 196, 198, 210, 215, 222, 226

Offset: 1

Benoit Cloitre, Mar 10 2002

If n=p-1, p prime, then n is in the sequence.

G. C. Greubel, Table of n, a(n) for n = 1..1000

Cf. A000225 (2^n-1), A038507 (n!+1).

Cf. A068480, A068481, A068483.

Filtered([1..230],n->Gcd(Factorial(n)+1,2^n-1)>1); # Muniru A Asiru, Oct 16 2018

select(n->gcd(factorial(n)+1,2^n-1)>1,[$1..230]); # Muniru A Asiru, Oct 16 2018

Select[Range[300],GCD[#!+1,2^#-1]>1&] (* Harvey P. Dale, Jan 31 2015 *)

isok(n) = gcd(n!+1,2^n-1) > 1; \\ Michel Marcus, Oct 16 2018

A067660 Values of gcd(k!+1,2^k+1) not equal to 1 taking k in increasing order.

Original entry on oeis.org

2, 11, 19, 43, 67, 131, 163, 179, 227, 347, 419, 443, 491, 523, 563, 571, 619, 683, 691, 739, 787, 947, 1019, 1051, 1091, 1123, 1187, 1291, 1451, 1499, 1571, 1579, 1667, 1723, 1747, 1867, 1907, 1931, 2003, 2131, 2203, 6043, 2347, 2371, 2531, 2579, 2659

Offset: 1

Benoit Cloitre, Feb 03 2002

nonn

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

Cf. A068481.

Table[GCD[n!+1,2^n+1],{n,0,4000}]/.(1->Nothing) (* Harvey P. Dale, Aug 03 2018 *)

for(k=0,3000,d=gcd(k!+1,2^k+1); if(d<>1,print1(d,",")))

If 2m+1 is prime and is in the sequence, 2m+1 = gcd(m!+1, 2^m+1).

Corrected and extended by Rick L. Shepherd, May 20 2002

Offset corrected by Amiram Eldar, Jun 06 2022

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A068480 Numbers n such that gcd(n!-1,2^n+1)>1.

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A068483 Numbers n such that gcd(n!-1,2^n-1)>1.

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A068482 Numbers n such that gcd(n!+1,2^n-1)>1.

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Maple

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A067660 Values of gcd(k!+1,2^k+1) not equal to 1 taking k in increasing order.

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