OFFSET
0,4
EXAMPLE
G.f.: A(x) = 1 + x + x^2 + 15*x^3 + 65*x^4 + 175*x^5 + 1155*x^6 + 7229*x^7 +...
where
A(x) = 1 +
x*((1-x) + x) +
x^2*((1-x)^2 + 2^4*x*(1-x) + x^2) +
x^3*((1-x)^3 + 3^4*x*(1-x)^2 + 3^4*x^2*(1-x) + x^3) +
x^4*((1-x)^4 + 4^4*x*(1-x)^3 + 6^4*x^2*(1-x)^2 + 4^4*x^3*(1-x) + x^4) +
x^5*((1-x)^5 + 5^4*x*(1-x)^4 + 10^4*x^2*(1-x)^3 + 10^4*x^3*(1-x)^2 + 5^4*x^4*(1-x) + x^5) +...
PROG
(PARI) {a(n)=polcoeff(sum(m=0, n+1, x^m*sum(k=0, m, binomial(m, k)^4*x^k*(1-x)^(m-k) + x*O(x^n))), n)}
for(n=0, 30, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Oct 23 2012
STATUS
approved