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%I #20 Jun 06 2022 05:47:35
%S 5,9,21,33,65,81,89,113,173,209,221,245,261,281,285,309,341,345,369,
%T 393,473,509,525,545,561,593,645,725,749,785,789,833,861,873,933,953,
%U 965,1001,1065,1101,1113,1173,1185,1265,1289,1329,1341,1401,1409,1469
%N Numbers k such that gcd(k!+1, 2^k+1) > 1.
%H Amiram Eldar, <a href="/A068481/b068481.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from G. C. Greubel)
%p select(n->gcd(factorial(n)+1,2^n+1)>1,[$1..1470]); # _Muniru A Asiru_, Oct 16 2018
%t Select[Range[2500], GCD[#! + 1, 2^# + 1] > 1 &] (* _G. C. Greubel_, Oct 15 2018 *)
%o (PARI) isok(n) = gcd(n!+1,2^n+1) > 1; \\ _Michel Marcus_, Oct 16 2018
%o (GAP) Filtered([1..1470],n->Gcd(Factorial(n)+1,2^n+1)>1); # _Muniru A Asiru_, Oct 16 2018
%Y Cf. A000051 (2^n+1), A038507 (n!+1).
%Y Cf. A068480, A068482, A068483.
%K easy,nonn
%O 1,1
%A _Benoit Cloitre_, Mar 10 2002
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