A115635 Periodic {1,1,-5,0,1,-3,-1,0,-3,1,-1,-4}.

1, 1, -5, 0, 1, -3, -1, 0, -3, 1, -1, -4, 1, 1, -5, 0, 1, -3, -1, 0, -3, 1, -1, -4, 1, 1, -5, 0, 1, -3, -1, 0, -3, 1, -1, -4, 1, 1, -5, 0, 1, -3, -1, 0, -3, 1, -1, -4, 1, 1, -5, 0, 1, -3, -1, 0, -3, 1, -1, -4, 1, 1, -5, 0, 1, -3, -1, 0, -3, 1, -1, -4

Offset: 0

Author

Paul Barry, Jan 27 2006

Keywords

• easy
• sign

Comments

Diagonal sums of number triangle A115633.

Links

• Index entries for linear recurrences with constant coefficients, signature (-1,-1,0,1,1,1).

Formula

G.f.: (1+2x-3x^2-4x^3-5x^4-4x^5)/((1-x^3)*(1+x+x^2+x^3)); a(n)=sum{k=0..floor(n/2), A115633(n-k, k)}.