A112808 Expansion of solution of functional equation.

1, 1, 2, 5, 14, 43, 142, 495, 1794, 6683, 25388, 97852, 381406, 1500317, 5947798, 23739795, 95326150, 384845581, 1561220986, 6361205709, 26021379044, 106826116871, 439987835410, 1817594141822, 7529012424286, 31265738342993

Offset

0,3

Links

Table of n, a(n) for n=0..25.

Formula

Given g.f. A(x), then series reversion of B(x)=x*A(x^3) is -B(-x).

Given g.f. A(x), then y=x*A(x^3) satisfies y=x+(xy)^2/(1-(xy)^6).

Prog

(PARI) {a(n)=local(A); if(n<0, 0, A=x+O(x^4); for(k=1, n, A=x+subst(x^2/(1-x^6), x, x*A)); polcoeff(A, 3*n+1))}

Crossrefs

Sequence in context: A123020 A005317 A126566 * A369158 A088927 A110489

Adjacent sequences: A112805 A112806 A112807 * A112809 A112810 A112811

Keyword

nonn

Author

Michael Somos, Sep 20 2005

Status

approved