A068480 -id:A068480 - cp's OEIS frontend

A068481 Numbers k such that gcd(k!+1, 2^k+1) > 1.

5, 9, 21, 33, 65, 81, 89, 113, 173, 209, 221, 245, 261, 281, 285, 309, 341, 345, 369, 393, 473, 509, 525, 545, 561, 593, 645, 725, 749, 785, 789, 833, 861, 873, 933, 953, 965, 1001, 1065, 1101, 1113, 1173, 1185, 1265, 1289, 1329, 1341, 1401, 1409, 1469

Offset: 1

Benoit Cloitre, Mar 10 2002

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from G. C. Greubel)

Cf. A000051 (2^n+1), A038507 (n!+1).

Cf. A068480, A068482, A068483.

Filtered([1..1470],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..1470]); # 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

A133382 Numbers n such that gcd( n!-1, 2^n-1 ) is neither 1 nor 2n+1.

Original entry on oeis.org

75, 525, 3940

Offset: 1

M. F. Hasler, Oct 28 2007

This subsequence of A068483 lists the rare exceptions for which gcd( N!, 2^N-1 ) <> 2N+1. Is it finite? Are all elements multiples of 5?

Cf. A068483, A068480.

for(n=1,10^5,if((g=gcd(n!-1,2^n-1)-1) & g!=2*n,print(n", ")))

cp's OEIS Frontend

A068481 Numbers k such that gcd(k!+1, 2^k+1) > 1.

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

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Mathematica

PARI

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

Views

Author

Keywords

Comments

Links

Crossrefs

Programs

GAP

Maple

Mathematica

PARI

A133382 Numbers n such that gcd( n!-1, 2^n-1 ) is neither 1 nor 2n+1.

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Author

Keywords

Comments

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PARI