login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A000163 Series-parallel numbers.
(Formerly M1852 N0732)
1
2, 8, 34, 136, 538, 2080, 7970, 30224, 113874, 426520, 1590338, 5906640, 21866794, 80725280, 297292610, 1092539736, 4007553922, 14675748416, 53663197698, 195962433328, 714734393378, 2603994002280, 9477643739746, 34463730424720 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
REFERENCES
J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 142.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
FORMULA
G.f.: 2*(1+S)/(1-S)^3, where S = g.f. for A000084. [Sean A. Irvine, Oct 14 2009]
MATHEMATICA
n = 25; s = 1/(1 - x) + O[x]^(n + 1); Do[s = s/(1 - x^k)^Coefficient[s, x^k] + O[x]^(n + 1), {k, 2, n}] ; S = s - 1; CoefficientList[2*(1 + S)/(1 - S)^3 + O[x]^n, x] (* Jean-François Alcover, Feb 09 2016 *)
CROSSREFS
Sequence in context: A204090 A226495 A111643 * A117616 A345757 A369836
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Sean A. Irvine, Oct 14 2009
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 06:57 EDT 2024. Contains 371265 sequences. (Running on oeis4.)