OFFSET
0,2
FORMULA
G.f. A(x) satisfies:
(1) A(x) = 1/( 1 - x*A(x)^(4/3)/(1 + x*A(x)) )^3.
(2) A(x) = 1 + x * A(x) * (1 + A(x)^(2/3) + A(x)^(4/3)).
(3) A(x) = B(x)^3 where B(x) is the g.f. of A271469.
If g.f. satisfies A(x) = ( 1 + x*A(x)^(t/r) * (1 + x*A(x)^(u/r))^s )^r, then a(n) = r * Sum_{k=0..n} binomial(t*k+u*(n-k)+r,k) * binomial(s*k,n-k)/(t*k+u*(n-k)+r).
PROG
(PARI) a(n, r=3, s=-1, t=5, u=3) = r*sum(k=0, n, binomial(t*k+u*(n-k)+r, k)*binomial(s*k, n-k)/(t*k+u*(n-k)+r));
CROSSREFS
KEYWORD
nonn,new
AUTHOR
Seiichi Manyama, Dec 11 2024
STATUS
approved