A026624 a(n) = Sum{T(i,j)}, 0<=i<=n, 0<=j<=n, T given by A026615.

1, 3, 8, 20, 46, 100, 210, 432, 878, 1772, 3562, 7144, 14310, 28644, 57314, 114656, 229342, 458716, 917466, 1834968, 3669974, 7339988, 14680018, 29360080, 58720206, 117440460, 234880970, 469761992, 939524038, 1879048132

Offset

0,2

Links

Table of n, a(n) for n=0..29.

Formula

G.f.: (1-x+x^2+x^3)/[(1-x)^2*(1-2x)] (conjectured). Cf. A026622. - Ralf Stephan, Feb 05 2004

Crossrefs

Sequence in context: A191522 A140481 A027928 * A026690 A036676 A101533

Adjacent sequences: A026621 A026622 A026623 * A026625 A026626 A026627

Keyword

nonn

Author

Clark Kimberling

Status

approved