A087968 a(n) = gcd(1 + 2^n, n^2).

1, 1, 9, 1, 1, 1, 1, 1, 27, 25, 1, 1, 1, 1, 9, 1, 1, 1, 1, 1, 9, 1, 1, 1, 1, 1, 81, 1, 1, 25, 1, 1, 9, 1, 1, 1, 1, 1, 9, 1, 1, 1, 1, 1, 27, 1, 1, 1, 1, 125, 9, 1, 1, 1, 121, 1, 9, 1, 1, 1, 1, 1, 27, 1, 1, 1, 1, 289, 9, 25, 1, 1, 1, 1, 9, 1, 1, 169, 1, 1, 243, 1, 1, 1, 1, 1, 9, 1, 1, 25, 1, 1, 9, 1, 1, 1

Offset: 1

Author

Labos Elemer, Sep 22 2003

Keywords

• nonn

Examples

			a(9) = gcd(2^9 + 1,9^2) = gcd(513,81) = 27.
		

Links

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

Crossrefs

Cf. A087966, A087969.

Programs

GAP

List([1..100],n->Gcd(2^n+1,n^2)); # Muniru A Asiru, Sep 22 2018

Maple

seq(gcd(2^n+1,n^2),n=1..100); # Muniru A Asiru, Sep 22 2018

PARI

A087968(n) = gcd((2^n)+1, n^2); \\ Antti Karttunen, Sep 22 2018