A137155 a(n) = Sum_{k=0..[n/2]} C(2^k + n-2k-1, n-2k); equals the antidiagonal sums of triangle A137153.

1, 1, 2, 3, 5, 9, 17, 35, 80, 201, 561, 1771, 6298, 25217, 115440, 605243, 3609754, 24742305, 196470603, 1792166979, 18817616610, 230233601737, 3268914688382, 53509699527491, 1020486454701731, 22777217813040393, 589097686208575727

Offset: 0

Author

Paul D. Hanna, Jan 24 2008

Keywords

• nonn

Crossrefs

Cf. A137153, A137154.

Programs

PARI

a(n)=sum(k=0,n\2,binomial(2^k+n-2*k-1,n-2*k))