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 A130119 a(n) = gcd(n^2 - 19, 45). 0

%I

%S 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,

%T 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,

%U 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

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

%C 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.

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

%t Table[GCD[n^2 - 19, 45], {n, 1, 100}] (* _Stefan Steinerberger_, May 17 2007 *)

%o (PARI) a(n) = gcd(n^2 - 19, 45); \\ _Michel Marcus_, Mar 23 2016

%K nonn

%O 1,1

%A _Zak Seidov_, May 14 2007, corrected May 16 2007

%E Better definition from _Stefan Steinerberger_, May 17 2007

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Last modified December 7 17:25 EST 2022. Contains 358668 sequences. (Running on oeis4.)