A089509 - OEIS

A089509

a(n) = Kronecker(7/n).

1, 1, 1, 1, -1, 1, 0, 1, 1, -1, -1, 1, -1, 0, -1, 1, -1, 1, 1, -1, 0, -1, -1, 1, 1, -1, 1, 0, 1, -1, 1, 1, -1, -1, 0, 1, 1, 1, -1, -1, -1, 0, -1, -1, -1, -1, 1, 1, 0, 1, -1, -1, 1, 1, 1, 0, 1, 1, 1, -1, -1, 1, 0, 1, 1, -1, -1, -1, -1, 0, -1, 1, -1, 1, 1, 1, 0, -1, -1, -1, 1, -1, 1, 0, 1, -1, 1, -1, -1, -1, 0, -1, 1, 1, -1, 1, -1, 0, -1, 1, -1, -1, 1, -1, 0, 1

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OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Jean-Paul Allouche, Leo Goldmakher, Mock characters and the Kronecker symbol, arXiv:1608.03957 [math.NT], 2016.

FORMULA

if n==0 (mod 7) a(n)=0; for p in=A003632 a(p)=-1; for p in A038878 a(p)=+1

MATHEMATICA

Table[KroneckerSymbol[7, n], {n, 100}] (* Vincenzo Librandi, Aug 16 2016 *)

PROG

(PARI) a(n)=kronecker(7, n)