A213906 G.f. satisfies: A(x) = x^2/(1-x) + A(A(x)).

1, 1, 2, 3, 7, 14, 36, 85, 226, 577, 1561, 4158, 11413, 31200, 86722, 241227, 677729, 1908832, 5411431, 15386107, 43949347, 125896209, 361904137, 1043032250, 3014490719, 8732211825, 25353395331, 73759912892, 215007439768, 627844428958, 1836466543942

Offset

2,3

Links

Table of n, a(n) for n=2..32.

Example

 G.f.: A(x) = x^2 + x^3 + 2*x^4 + 3*x^5 + 7*x^6 + 14*x^7 + 36*x^8 + 85*x^9 +...
where
A(A(x)) = x^4 + 2*x^5 + 6*x^6 + 13*x^7 + 35*x^8 + 84*x^9 + 225*x^10 +...

Prog

 (PARI) {a(n)=local(A=x^2+x^3); for(i=1, n, A=x^2/(1-x+x*O(x^n))+subst(A, x, A+x*O(x^n))); polcoeff(A, n)}
for(n=2, 40, print1(a(n), ", "))

Crossrefs

Cf. A213905.

Sequence in context: A210345 A006660 A306844 * A364593 A123777 A245899

Adjacent sequences: A213903 A213904 A213905 * A213907 A213908 A213909

Keyword

nonn

Author

Paul D. Hanna, Jun 24 2012

Status

approved