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

Offset: 1

Author

Benoit Cloitre, Jan 03 2004

Keywords

• sign
• mult

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.

Crossrefs

Cf. A091338, A080891.

Programs

Magma

[KroneckerSymbol(7,n): n in [1..100]]; // Vincenzo Librandi, Aug 16 2016

Mathematica

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

PARI

a(n)=kronecker(7,n)

Formula

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

Extensions

Keyword:mult added by Andrew Howroyd, Jul 23 2018