This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A128553 #3 Mar 30 2012 18:37:03 %S A128553 1,5,18,58,155,383,867,1860,3782,7409,13989,25683,45905,80262,137453, %T A128553 231269,382689,624061,1003787,1594796,2504587,3892100,5988403,9129707, %U A128553 13798792,20688367,30781988,45473815,66723042,97276842,140959603 %N 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]. %o A128553 (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) %Y A128553 Cf. A128545; A128552, A128554. %K A128553 nonn %O A128553 0,2 %A A128553 _Paul D. Hanna_, Mar 10 2007