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A026845
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Sum_{mu a partition of n} (f^mu/n!)^{-2} where f^mu is the number of standard Young tableaux of shape mu.
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0
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1, 8, 81, 1424, 32152, 1144937, 53178768, 3360267976, 268737034880, 26735641360265, 3222856389284352, 463078022054303432, 78131995260953112576, 15295767841794798044432, 3438384401028669096232665
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OFFSET
| 0,2
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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)
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MATHEMATICA
| (* version 4.0 *) Needs["DiscreteMath`Combinatorica`]; Table[Tr[(n!/(NumberOfTableaux /@ Partitions[n]))^2], {n, 20}] [From Wouter Meeussen (wouter.meeussen(AT)pandora.be), Sep 30 2010]
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CROSSREFS
| Cf. A047874 [From Wouter Meeussen (wouter.meeussen(AT)pandora.be), Sep 30 2010]
Sequence in context: A022519 A138439 A193563 * A145921 A100399 A022504
Adjacent sequences: A026842 A026843 A026844 * A026846 A026847 A026848
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KEYWORD
| nonn
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AUTHOR
| Bruce Sagan (sagan(AT)math.msu.edu), Apr 06 2002
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EXTENSIONS
| Terms 8 to 20 added. Wouter Meeussen (wouter.meeussen(AT)pandora.be), Sep 30 2010
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