OFFSET
1,1
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = 2*A086933(n). - Andrew Howroyd, Aug 07 2018
MATHEMATICA
A[n_] := Sum[If[Mod[a^2+b^2, 2n] == n, 1, 0], {a, 0, 2n - 1}, {b, 0, 2n - 1}]; Array[A, 100]
PROG
(PARI) a(n)={my(m=2*n); my(p=Mod(sum(i=0, m-1, x^(i^2%m)), x^m-1)^2); polcoeff( lift(p), n)} \\ Andrew Howroyd, Aug 07 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
José María Grau Ribas, Sep 22 2013
STATUS
approved