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Search: id:A006411
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| A006411 |
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Nonseparable planar tree-rooted maps.
(Formerly M3073)
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+0
2
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| 3, 20, 75, 210, 490, 1008, 1890, 3300, 5445, 8580, 13013, 19110, 27300, 38080, 52020, 69768, 92055, 119700, 153615, 194810, 244398, 303600, 373750, 456300, 552825, 665028, 794745, 943950, 1114760, 1309440
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Walsh, T. R. S.; Lehman, A. B.; Counting rooted maps by genus. III: Nonseparable maps. J. Combinatorial Theory Ser. B 18 (1975), 222-259.
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FORMULA
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G.f.: (3+2*x)/(1-x)^6.
a(n)=A027777(n)/2 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 23 2007
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MAPLE
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a:=n->(sum((numbcomp(n, 5)), j=3..n)):seq(a(n), n=5..34); [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Aug 26 2008]
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MATHEMATICA
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Table[(Binomial[i+2, 3])*(Binomial[i+3, 2])/2, {i, 0, 30}] Table[StirlingS2[i+1, i]Binomial[i, 3]/2, {i, 2, 32}] - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 23 2007
Table[Sum[Binomial[n, 4], {i, 2, n}], {n, 4, 41}] [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jul 10 2009]
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CROSSREFS
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Cf. A027777.
Sequence in context: A024402 A067600 A160456 this_sequence A129549 A092786 A015529
Adjacent sequences: A006408 A006409 A006410 this_sequence A006412 A006413 A006414
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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