login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

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 December 14 15:08 EST 2019. Contains 329979 sequences. (Running on oeis4.)