A089145 Greatest common divisor of n^2-3 and n^2+3.

3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1

Offset: 0

Author

Cino Hilliard, Dec 05 2003

Keywords

• easy
• nonn

Links

• Colin Barker, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,1).

Programs

PARI

g(n) = for(x=0,n,print1(gcd(x^2-3,x^2+3)","))

PARI

Vec((3 + 2*x + x^2 + 6*x^3 + x^4 + 2*x^5) / ((1 - x)*(1 + x)*(1 - x + x^2)*(1 + x + x^2)) + O(x^80)) \\ Colin Barker, Dec 11 2019

Formula

From Colin Barker, Dec 11 2019: (Start)

G.f.: (3 + 2*x + x^2 + 6*x^3 + x^4 + 2*x^5) / ((1 - x)*(1 + x)*(1 - x + x^2)*(1 + x + x^2)).

a(n) = a(n-6) for n>5.

(End)