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Search: id:A007165
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| A007165 |
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Number of P-graphs with 2n edges.
(Formerly M0873)
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+0
1
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| 1, 1, 2, 3, 8, 14, 42, 79, 252, 494, 1636, 3294, 11188, 22952, 79386, 165127, 579020, 1217270, 4314300, 9146746, 32697920, 69799476, 251284292, 539464358, 1953579240, 4214095612, 15336931928, 33218794236, 121416356108
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math., 31 (1986), 47-63.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math. 31 (1986) no 1, 47-63
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MAPLE
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bq := proc(q::integer) local m; if q mod 2 = 0 then RETURN(0); else m:=(q-1)/2; RETURN( sum(binomial(q, s)*binomial(s+m-1, m), s=0..q)/(q*2^(m+1)) ); fi; end: H := proc(maxord::integer) local resul, r, B; resul := 0; B := 0; for r from 2 to maxord by 2 do B := B+bq(r/2)*y^r; od : for r from 1 to maxord/2 do resul := resul + B^r; od : RETURN(resul); end: maxord := 60 : Hser := expand(H(maxord)) : for n from 2 to maxord by 2 do simplify(coeftayl(Hser, y=0, n)); od; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 24 2006
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CROSSREFS
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Sequence in context: A129700 A049344 A080877 this_sequence A107321 A005316 A076876
Adjacent sequences: A007162 A007163 A007164 this_sequence A007166 A007167 A007168
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KEYWORD
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nonn
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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 Pab Ter (pabrlos(AT)yahoo.com), May 27 2004
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