|
%I #28 Apr 04 2020 11:04:58
%S 1,1,2,6,14,41,157,725,4196,29816,246644,2297075,23503477,260265023,
%T 3090336300,39101547971,524782945991,7443247863498,111221983956652,
%U 1746165682538497,28734206614035245,494526496354065244,8883865784392246280,166286434745252091055,3237719048384605059117,65477287940472122129194
%N Number of simple regular trivalent bipartite graphs with 2n nodes.
%C Euler transform of A006823. - _Peter J. Taylor_, Sep 28 2017
%H G. Brinkmann, <a href="http://dx.doi.org/10.1002/(SICI)1097-0118(199610)23:2<139::AID-JGT5>3.0.CO;2-U">Fast generation of cubic graphs</a>, Journal of Graph Theory, 23(2):139-149, 1996.
%H Sean A. Irvine, <a href="/A008325/a008325.png">On the difference between A004066 and A008325</a>
%t A006823 = Cases[Import["https://oeis.org/A006823/b006823.txt", "Table"], {_, _}][[All, 2]];
%t etr[f_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d f[d], {d, Divisors[j]}] b[n - j], {j, 1, n}]/n]; b];
%t b[n_] := If[n >= 3, A006823[[n - 2]], 0];
%t a = etr[b];
%t a /@ Range[3, 16] (* _Jean-François Alcover_, Dec 03 2019 *)
%Y Column k=3 of A008327.
%Y Cf. A004066 (bicolored), A006823 (connected).
%K nonn,hard
%O 3,3
%A _Brendan McKay_
%E a(15)-a(16) from _Peter J. Taylor_, Sep 28 2017
%E Terms a(17) and beyond from _Andrew Howroyd_, Apr 03 2020
|
