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A320993
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Number of connected self-dual marked graphs on 2n nodes.
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1
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1, 1, 6, 81, 2796, 285205, 96322648, 112087066485, 458071927263177, 6665704296474517580, 349377209492189224235030, 66602723163954143548104716149, 46557323273646194397454383970079368, 120168498151800396724425771086539073209571, 1152049915423012273792614840558950392103437052846
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OFFSET
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0,3
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LINKS
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Andrew Howroyd, Table of n, a(n) for n = 0..50
Edward A. Bender and E. Rodney Canfield, Enumeration of connected invariant graphs, Journal of Combinatorial Theory, Series B 34.3 (1983): 268-278. See p. 274.
Andrew Howroyd, PARI Program
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FORMULA
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a(2*n-1) = b(2*n-1) - A054921(2*n-1)/2, a(2*n) = b(2*n) - (A054921(2*n)-a(n))/2 where b is the Inverse Euler transform of A000595. - Andrew Howroyd, Jan 27 2020
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PROG
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(PARI) \\ See link for program.
A320993seq(15) \\ Andrew Howroyd, Jan 27 2020
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CROSSREFS
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Cf. A000666 (not necessarily connected marked graphs), A000595 (self dual on 2n nodes), A054921 (connected marked graphs).
Sequence in context: A076282 A121790 A279203 * A032491 A135624 A222197
Adjacent sequences: A320990 A320991 A320992 * A320994 A320995 A320996
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, Oct 26 2018
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EXTENSIONS
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a(0)=1 prepended and terms a(7) and beyond from Andrew Howroyd, Jan 26 2020
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STATUS
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approved
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