OFFSET
0,3
COMMENTS
LINKS
Eric Weisstein's World of Mathematics, q-Factorial.
EXAMPLE
a(n) is the central term of the q-analog of even double factorials,
in which the coefficients of q (triangle A128084) begin:
n=0: (1);
n=1: (1),1;
n=2: 1,2,(2),2,1;
n=3: 1,3,5,7,(8),8,7,5,3,1;
n=4: 1,4,9,16,24,32,39,44,(46),44,39,32,24,16,9,4,1;
n=5: 1,5,14,30,54,86,125,169,215,259,297,325,(340),340,325,297,...;...
The terms enclosed in parenthesis are initial terms of this sequence.
PROG
(PARI) a(n)=if(n==0, 1, polcoeff(prod(k=1, n, (1-q^(2*k))/(1-q)), n^2\2, q))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Feb 14 2007
STATUS
approved