OFFSET
0,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..310
EXAMPLE
G.f.: A(x) = 1 + x + 2*x^2 + 7*x^3 + 36*x^4 + 252*x^5 + 2278*x^6 +...
where
A(x) = 1 + x/(1-x) + x^2/((1-2*x)*(1-3*x)) + x^3/((1-4*x)*(1-5*x)*(1-6*x)) + x^4/((1-7*x)*(1-8*x)*(1-9*x)*(1-10*x)) + x^5/((1-11*x)*(1-12*x)*(1-13*x)*(1-14*x)*(1-15*x)) +...
PROG
(PARI) {a(n)=polcoeff(sum(m=0, n, x^m/prod(k=m*(m-1)/2+1, m*(m+1)/2, 1-k*x +x*O(x^n))), n)}
for(n=0, 30, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 02 2014
STATUS
approved