OFFSET
0,2
PROG
(PARI) a(n)=binomial(n*(n+1)/2+n+1, n)
(Sage) [binomial(binomial(binomial(n+1, n), n-1), n-1) for n in range(1, 19)] # Zerinvary Lajos, Nov 30 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jun 04 2005
STATUS
approved