A117946 a(3n)=0, a(3n+1)/a(1)=a(3n+2)/a(2)=A059151(n).

0, 1, -2, 0, 2, -4, 0, 1, -2, 0, 2, -4, 0, 4, -8, 0, 2, -4, 0, 1, -2, 0, 2, -4, 0, 1, -2, 0, 2, -4, 0, 4, -8, 0, 2, -4, 0, 4, -8, 0, 8, -16, 0, 4, -8, 0, 2, -4, 0, 4, -8, 0, 2, -4, 0, 1, -2, 0, 2, -4, 0, 1, -2, 0, 2, -4, 0, 4, -8, 0, 2, -4, 0, 1, -2, 0, 2, -4, 0, 1, -2, 0, 2, -4, 0, 4, -8, 0, 2, -4, 0, 4, -8, 0, 8, -16, 0, 4, -8

Offset: 0

Author

Paul Barry, Apr 05 2006

Keywords

• easy
• sign

Comments

Second column of A117939.

Formula

a(n)=sum{k=0..n, L((n-k)/3)*L(C(n,k)/3)} where L(j/p) is the Legendre symbol of j and p.