OFFSET
0,2
FORMULA
PROG
(PARI) {a(n)=local(M); M=matrix(n+3, n+3, r, c, if(r<c, 0, if(r==0, 1, polcoeff(prod(j=r+1, 2*r, 1-q^j)/prod(j=1, r, 1-q^j), (r+1)*(c-1), q)))); (M^2)[n+3, 3]}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Mar 12 2007
STATUS
approved