A128553 Column 3 of triangle A128545; a(n) is the coefficient of q^(3n+9) in the central q-binomial coefficient [2n+6,n+3].

1, 5, 18, 58, 155, 383, 867, 1860, 3782, 7409, 13989, 25683, 45905, 80262, 137453, 231269, 382689, 624061, 1003787, 1594796, 2504587, 3892100, 5988403, 9129707, 13798792, 20688367, 30781988, 45473815, 66723042, 97276842, 140959603

Offset: 0

Author

Paul D. Hanna, Mar 10 2007

Keywords

• nonn

Crossrefs

Cf. A128545; A128552, A128554.

Programs

PARI

a(n)=polcoeff(prod(j=n+4,2*n+6,1-q^j)/prod(j=1,n+3,1-q^j),3*n+9,q)