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

75, 525, 3940

Offset: 1

Author

M. F. Hasler, Oct 28 2007

Keywords

• nonn
• bref

Comments

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?

Crossrefs

Cf. A068483, A068480.

Programs

PARI

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