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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A007801 Expansion of f(f(x)), where f = x + x^2 + x^4 + x^8 + x^16 + ... 1
1, 2, 2, 3, 6, 8, 8, 16, 22, 40, 80, 146, 240, 356, 488, 661, 870, 1184, 1936, 3750, 7976, 17628, 37528, 74828, 140480, 249444, 420392, 678432, 1056600, 1593512, 2334928, 3337410, 4660246, 6364080, 8527984, 11258182, 14753032, 19622940, 27836440 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..1023

FORMULA

a(n) = sum(k=1..n, A073266(n,k)*f(k)). - Vladimir Kruchinin, Mar 13 2012

MAPLE

e:= 8;

f:= x -> sum(x^(2^i), i=0..e):

g:= f(f(x)):

S:= series(g, x, 2^e):

seq(coeff(S, x, n), n=0..2^e-1); # Robert Israel, Aug 19 2014

CROSSREFS

Sequence in context: A303028 A011141 A159915 * A275493 A193595 A077871

Adjacent sequences:  A007798 A007799 A007800 * A007802 A007803 A007804

KEYWORD

nonn

AUTHOR

Jeffrey Shallit

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 October 18 10:59 EDT 2019. Contains 328147 sequences. (Running on oeis4.)