OFFSET
0,2
COMMENTS
Sum_{n>=0} x^(n*(n+1)/2) / Product_{k=0..n} (1 + x^(k+1)) = 1.
What does this sequence count?
PROG
(PARI) N=66; x='x + O('x^N); s =sum(n=0, N, x^(n*(n+1)/2) * prod(k=0, n, 1+x^(k+1) ) ); v=Vec(s)
CROSSREFS
KEYWORD
nonn
AUTHOR
Joerg Arndt, Aug 14 2011
STATUS
approved