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A320995 Number of connected self-dual nets with 2n nodes. 1
1, 0, 5, 136, 24162, 29488085, 286615837574, 21717610066598371, 12980514969049888065118, 62082684164458190567999459967, 2405195234525224724112302276711929089, 762399076229936058613587754015434541854738381 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..40

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. 275.

Andrew Howroyd, PARI Program

FORMULA

a(2*n-1) = b(2*n-1) - A320489(2*n-1)/2, a(2*n) = b(2*n) - (A320489(2*n)-a(n))/2 where b is the Inverse Euler transform of A004107. - Andrew Howroyd, Jan 27 2020

PROG

(PARI) \\ See link for program.

A320995seq(15) \\ Andrew Howroyd, Jan 27 2020

CROSSREFS

Cf. A004103 (not necessarily connected nets), A004107 (self-dual), A320489 (connected nets).

Sequence in context: A082212 A208867 A094808 * A061453 A215958 A216337

Adjacent sequences:  A320992 A320993 A320994 * A320996 A320997 A320998

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 January 17 10:38 EST 2021. Contains 340214 sequences. (Running on oeis4.)