OFFSET
0,2
COMMENTS
Equals column 3 of triangle A325580.
EXAMPLE
G.f.: A(x) = 1 + 4*x + 26*x^2 + 144*x^3 + 861*x^4 + 5300*x^5 + 33974*x^6 + 226716*x^7 + 1572134*x^8 + 11318196*x^9 + 84460828*x^10 + 652359324*x^11 + ...
such that
A(x) = 1 + 4*x*(1+x)^4 + 10*x^2*(1+x)^10 + 20*x^3*(1+x)^18 + 35*x^4*(1+x)^28 + 56*x^5*(1+x)^40 + 84*x^6*(1+x)^54 + 120*x^7*(1+x)^70 + 165*x^8*(1+x)^88 + ...
PROG
(PARI) {a(n) = my(A = sum(m=0, n, (m+1)*(m+2)*(m+3)/3! * x^m * (1+x +x*O(x^n))^(m*(m+3)) )); polcoeff(A, n)}
for(n=0, 30, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, May 11 2019
STATUS
approved