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A006470
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Number of rooted planar maps.
(Formerly M2075)
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2
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2, 15, 60, 175, 420, 882, 1680, 2970, 4950, 7865, 12012, 17745, 25480, 35700, 48960, 65892, 87210, 113715, 146300, 185955, 233772, 290950, 358800, 438750, 532350, 641277, 767340, 912485, 1078800, 1268520
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| 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
| (n+1)*binomial(n+3, 4).
C(n+2, 2)*C(n+4, 3)/2; g.f.: x*(2+3*x)/(1-x)^6. - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 14 2005
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MATHEMATICA
| f[n_]:=(n+(n+1)+(n+2))*n*(n+1)*(n+2)*(n+3)/72; lst={}; Do[AppendTo[lst, f[n]], {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Oct 08 2009]
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CROSSREFS
| A027789/2.
Sequence in context: A034571 A126019 A071237 * A084169 A000181 A047146
Adjacent sequences: A006467 A006468 A006469 * A006471 A006472 A006473
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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