OFFSET
0,3
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..500
FORMULA
G.f.: A(x) satisfies A(x) = G(x*A(x)^2) where G(x) + 2*x is the g.f. of A004304.
PROG
(PARI) \\ here J(n) gives A004304 as g.f.
J(n)={my(g=(1-sqrt(1-4*x+O(x^3*x^n)))/(2*x), h=serconvol(g, (g-1)/x)); sqrt(x/serreverse(x*h^2))}
seq(n)={my(g=J(n)-2*x, p=O(1)); while(serprec(p, x)<=n, p = subst(g, x, x*p^2)); Vec(p)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Apr 03 2021
STATUS
approved