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A006428
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Tree-rooted planar maps.
(Formerly M3139)
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0
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0, 3, 36, 135, 360, 798, 1568, 2826, 4770, 7645, 11748, 17433
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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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
| a(n) seems to be divisible by n+1. - Ralf Stephan (ralf(AT)ark.in-berlin.de), Sep 01 2003
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CROSSREFS
| Sequence in context: A140958 A156189 A158077 * A068619 A168075 A188891
Adjacent sequences: A006425 A006426 A006427 * A006429 A006430 A006431
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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