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A320995 Number of connected self-dual nets with 2n nodes. 1


%S 1,0,5,136,24162,29488085,286615837574,21717610066598371,

%T 12980514969049888065118,62082684164458190567999459967,

%U 2405195234525224724112302276711929089,762399076229936058613587754015434541854738381

%N Number of connected self-dual nets with 2n nodes.

%H Andrew Howroyd, <a href="/A320995/b320995.txt">Table of n, a(n) for n = 0..40</a>

%H Edward A. Bender and E. Rodney Canfield, <a href="https://doi.org/10.1016/0095-8956(83)90040-0">Enumeration of connected invariant graphs</a>, Journal of Combinatorial Theory, Series B 34.3 (1983): 268-278. See p. 275.

%H Andrew Howroyd, <a href="/A320995/a320995.txt">PARI Program</a>

%F 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

%o (PARI) \\ See link for program.

%o A320995seq(15) \\ _Andrew Howroyd_, Jan 27 2020

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

%K nonn

%O 0,3

%A _N. J. A. Sloane_, Oct 26 2018

%E a(0)=1 prepended and terms a(7) and beyond from _Andrew Howroyd_, Jan 26 2020

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Last modified March 7 09:46 EST 2021. Contains 341869 sequences. (Running on oeis4.)