A087966 a(n) = gcd(-1 + 2^n, n^2).

1, 1, 1, 1, 1, 9, 1, 1, 1, 1, 1, 9, 1, 1, 1, 1, 1, 27, 1, 25, 49, 1, 1, 9, 1, 1, 1, 1, 1, 9, 1, 1, 1, 1, 1, 27, 1, 1, 1, 25, 1, 441, 1, 1, 1, 1, 1, 9, 1, 1, 1, 1, 1, 81, 1, 1, 1, 1, 1, 225, 1, 1, 49, 1, 1, 9, 1, 1, 1, 1, 1, 27, 1, 1, 1, 1, 1, 9, 1, 25, 1, 1, 1, 441, 1, 1, 1, 1, 1, 27, 1, 1, 1, 1, 1, 9, 1, 1

Offset: 1

Author

Labos Elemer, Sep 22 2003

Keywords

• nonn

Examples

			a(6) = gcd(2^6 - 1,6^2) = gcd(64-1,36) = 9.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537

Crossrefs

Cf. A087967, A087968.

Programs

GAP

List([1..120],n->Gcd(2^n-1,n^2)); # Muniru A Asiru, Sep 22 2018

Maple

seq(gcd(2^n-1,n^2),n=1..120); # Muniru A Asiru, Sep 22 2018

PARI

A087966(n) = gcd((2^n)-1, n^2); \\ Antti Karttunen, Sep 22 2018