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Search: id:A006298
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| A006298 |
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Number of rooted genus-2 maps with n edges.
(Formerly M5117)
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+0
3
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| 21, 483, 6468, 66066, 570570, 4390386, 31039008, 205633428, 1293938646, 7808250450, 45510945480, 257611421340, 1422156202740, 7683009544980, 40729207226400, 212347275857640, 1090848505817070, 5530195966465170
(list; graph; listen)
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OFFSET
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4,1
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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).
T. R. S. Walsh, Combinatorial Enumeration of Non-Planar Maps. Ph.D. Dissertation, Univ. of Toronto, 1971.
T. R. S. Walsh and A. B. Lehman, Counting rooted maps by genus, J. Comb. Thy B13 (1972), 122-141 and 192-218.
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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FORMULA
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a(n+1) = ((5n+3)(4n+2)a(n))/((5n-2)(n-3))
G.f.: 21x^4(1+x)/sqrt[(1-x)^11]. a(n) = 21 * [A020922(n-4) + A020922(n-3)]. - R. Stephan, Mar 13 2004
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CROSSREFS
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Cf. A035309.
Sequence in context: A126996 A158603 A025603 this_sequence A089907 A015695 A006299
Adjacent sequences: A006295 A006296 A006297 this_sequence A006299 A006300 A006301
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from David W. Wilson (davidwwilson(AT)comcast.net)
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