login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A320994 Number of connected point-self-dual nets with 2n nodes. 1

%I

%S 1,2,37,3264,1798306,7066174625,208496688495494,47481277563116098111,

%T 85161165189313899034899294,1221965295353715648352925546245057,

%U 142024241427456183309163988600775633635361,135056692113925953789612785828652550808044930178235

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

%H Andrew Howroyd, <a href="/A320994/b320994.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. 274.

%H Andrew Howroyd, <a href="/A320994/a320994.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 A004105. - _Andrew Howroyd_, Jan 27 2020

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

%o A320994seq(15) \\ _Andrew Howroyd_, Jan 27 2020

%Y Cf. A004103 (nets), A004105 (point-self-dual on 2n nodes), A320489 (connected nets).

%K nonn

%O 0,2

%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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 15 14:25 EDT 2021. Contains 342977 sequences. (Running on oeis4.)