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 A320993 Number of connected self-dual marked graphs on 2n nodes. 1
 1, 1, 6, 81, 2796, 285205, 96322648, 112087066485, 458071927263177, 6665704296474517580, 349377209492189224235030, 66602723163954143548104716149, 46557323273646194397454383970079368, 120168498151800396724425771086539073209571, 1152049915423012273792614840558950392103437052846 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS 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 FORMULA 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 PROG (PARI) \\ See link for program. A320993seq(15) \\ Andrew Howroyd, Jan 27 2020 CROSSREFS 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 KEYWORD nonn AUTHOR N. J. A. Sloane, Oct 26 2018 EXTENSIONS a(0)=1 prepended and terms a(7) and beyond from Andrew Howroyd, Jan 26 2020 STATUS approved

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Last modified August 4 23:59 EDT 2024. Contains 374934 sequences. (Running on oeis4.)