login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A213906 G.f. satisfies: A(x) = x^2/(1-x) + A(A(x)). 1
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 (list; graph; refs; listen; history; text; internal format)
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 * A123777 A245899 A246747

Adjacent sequences:  A213903 A213904 A213905 * A213907 A213908 A213909

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jun 24 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 29 20:42 EDT 2020. Contains 334710 sequences. (Running on oeis4.)