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!)
A026845 Sum_{mu a partition of n} (f^mu/n!)^{-2} where f^mu is the number of standard Young tableaux of shape mu. 1
1, 8, 81, 1424, 32152, 1144937, 53178768, 3360267976, 268737034880, 26735641360265, 3222856389284352, 463078022054303432, 78131995260953112576, 15295767841794798044432, 3438384401028669096232665, 879589866427669147125523584, 254053056142392070125392290952 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Arises from counting coverings of a genus g=2 Riemann surface - expansion of generating function A_g(q) = sum_{n>=0} a_{n,g} q^n where a_{n,g} = sum_{mu a partition of n} (f^mu/n!)^{2-2g}; note that A_0(q) = e^q and A_1(q) = prod_{i>=1} 1/(1-q^i).

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..60

MATHEMATICA

(* version 4.0 *) Needs["DiscreteMath`Combinatorica`"]; Table[Tr[(n!/ (NumberOfTableaux /@ Partitions[n]))^2], {n, 20}] (* Wouter Meeussen, Sep 30 2010 *)

CROSSREFS

Cf. A047874. - Wouter Meeussen, Sep 30 2010

Sequence in context: A022519 A138439 A193563 * A305770 A145921 A304655

Adjacent sequences:  A026842 A026843 A026844 * A026846 A026847 A026848

KEYWORD

nonn

AUTHOR

Bruce E. Sagan, Apr 06 2002

EXTENSIONS

Terms 8 to 20 added by Wouter Meeussen, Sep 30 2010

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 October 1 19:48 EDT 2022. Contains 357172 sequences. (Running on oeis4.)