login
A112808
Expansion of solution of functional equation.
0
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
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
KEYWORD
nonn
AUTHOR
Michael Somos, Sep 20 2005
STATUS
approved