A099528 Row sums of triangle A099527, so that a(n) = Sum_{k=0..n} coefficient of z^k in (2 + 3*z + z^2)^(n-[k/2]), where [k/2] is the integer floor of k/2.

1, 5, 17, 63, 242, 922, 3502, 13311, 50608, 192398, 731429, 2780649, 10571120, 40187929, 152781292, 580824261, 2208102985, 8394481949, 31913061839, 121322974122, 461230079570, 1753445197282, 6666022438759, 25342026784200

Offset

0,2

Links

Table of n, a(n) for n=0..23.

Formula

G.f.: (1+x-x^2)/(1-4*x+2*x^2-5*x^3+x^4).

Prog

(PARI) a(n)=sum(k=0, n, polcoeff((2+3*z+z^2+z*O(z^k))^(n-k\2), k, z))

Crossrefs

Cf. A099527.

Sequence in context: A128073 A051736 A301560 * A149667 A149668 A149669

Adjacent sequences: A099525 A099526 A099527 * A099529 A099530 A099531

Keyword

nonn

Author

Paul D. Hanna, Oct 20 2004

Extensions

Corrected by T. D. Noe, Oct 25 2006

Status

approved