A115270 Diagonal sums of correlation triangle for floor((n+4)/4).

1, 1, 2, 3, 5, 6, 9, 11, 16, 19, 25, 30, 39, 45, 56, 65, 80, 91, 109, 124, 147, 165, 192, 215, 249, 276, 315, 349, 396, 435, 489, 536, 600, 654, 726, 790, 874, 946, 1040, 1124, 1232

Offset: 0

Author

Paul Barry, Jan 18 2006

Keywords

• easy
• nonn

Comments

Diagonal sums of number triangle A115268.

Formula

G.f.: (1+x+x^2+x^3)(1+x^2+x^4+x^6)/((1-x^4)^2*(1-x^8)^2*(1-x^3)); a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, [j<=k]*floor((k-j+4)/4)*[j<=n-2k]*floor((n-2k-j+4)/4)}}.