|
|
A068481
|
|
Numbers k such that gcd(k!+1, 2^k+1) > 1.
|
|
5
|
|
|
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
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MAPLE
|
select(n->gcd(factorial(n)+1, 2^n+1)>1, [$1..1470]); # Muniru A Asiru, Oct 16 2018
|
|
MATHEMATICA
|
Select[Range[2500], GCD[#! + 1, 2^# + 1] > 1 &] (* G. C. Greubel, Oct 15 2018 *)
|
|
PROG
|
(PARI) isok(n) = gcd(n!+1, 2^n+1) > 1; \\ Michel Marcus, Oct 16 2018
(GAP) Filtered([1..1470], n->Gcd(Factorial(n)+1, 2^n+1)>1); # Muniru A Asiru, Oct 16 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|