OFFSET
0,3
FORMULA
G.f. A(x) satisfies A(x) = 1/( 1 - x - x*Sum_{k=1..3} binomial(2,k-1) * x^k/k! * (d^k/dx^k A(x)) ).
PROG
(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, binomial(j+2, 3)*v[j+1]*v[i-j])); v;
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jul 22 2025
STATUS
approved
