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

75, 525, 3940

Offset

1,1

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?

Links

Table of n, a(n) for n=1..3.

Prog

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

Crossrefs

Cf. A068483, A068480.

Sequence in context: A223452 A015223 A129625 * A199901 A251249 A264673

Adjacent sequences: A133379 A133380 A133381 * A133383 A133384 A133385

Keyword

nonn,bref

Author

M. F. Hasler, Oct 28 2007

Status

approved