A130119 a(n) = gcd(n^2 - 19, 45).

9, 15, 5, 3, 3, 1, 15, 45, 1, 9, 3, 5, 15, 3, 1, 3, 45, 5, 9, 3, 1, 15, 15, 1, 3, 9, 5, 45, 3, 1, 3, 15, 5, 3, 9, 1, 45, 15, 1, 3, 3, 5, 15, 9, 1, 9, 15, 5, 3, 3, 1, 15, 45, 1, 9, 3, 5, 15, 3, 1, 3, 45, 5, 9, 3, 1, 15, 15, 1, 3, 9, 5, 45, 3, 1, 3, 15, 5, 3, 9, 1, 45, 15, 1, 3, 3, 5, 15, 9, 1, 9, 15, 5, 3, 3, 1, 15, 45, 1, 9, 3, 5, 15, 3, 1, 3, 45, 5, 9, 3, 1, 15

Offset

1,1

Comments

Has period of length 45: 9,15,5,3,3,1,15,45,1,9,3,5,15,3,1,3,45,5,9,3,1,15,15,1,3,9,5,45,3,1,3,15,5,3,9,1,45,15,1,3,3,5,15,9,1.

Links

Table of n, a(n) for n=1..112.

Formula

a(n) = gcd((7n^2+2), (2n^2+7)).

Mathematica

Table[GCD[n^2 - 19, 45], {n, 1, 100}] (* Stefan Steinerberger, May 17 2007 *)

Prog

(PARI) a(n) = gcd(n^2 - 19, 45); \\ Michel Marcus, Mar 23 2016

Crossrefs

Sequence in context: A370674 A131224 A073920 * A346609 A232395 A184048

Adjacent sequences: A130116 A130117 A130118 * A130120 A130121 A130122

Keyword

nonn

Author

Zak Seidov, May 14 2007, corrected May 16 2007

Extensions

Better definition from Stefan Steinerberger, May 17 2007

Status

approved