A027909 T(2n,n-1), T given by A027907.

1, 4, 21, 112, 615, 3432, 19383, 110448, 633726, 3656360, 21191555, 123286440, 719539015, 4210967880, 24702429825, 145210795200, 855172338570, 5044470461352, 29799593861974, 176268499363840, 1043889366927771, 6188748520285584, 36726461258947569, 218146172715259488, 1296812014083995850

Offset

0,2

Links

Table of n, a(n) for n=0..24.

Formula

G.f.: -g*(g^2+g+1)/(3*g^2+g-1) where g = x times the g.f. of A143927. - Mark van Hoeij, Nov 16 2011

Maple

seq(add(binomial(j, 2*j-3*n-4)*binomial(2*n+2, j), j=0...2*n+2), n=0..25);  # Mark van Hoeij, May 12 2013

Prog

(PARI) a(n)=sum(j=0, 2*n+2, binomial(j, 2*j-3*n-4)*binomial(2*n+2, j)); \\ Joerg Arndt, May 13 2013~

Crossrefs

Sequence in context: A136786 A301972 A026335 * A127111 A270787 A190089

Adjacent sequences: A027906 A027907 A027908 * A027910 A027911 A027912

Keyword

nonn

Author

Clark Kimberling

Extensions

Corrected offset, more terms, Joerg Arndt, May 13 2013

Status

approved