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%I #22 Mar 15 2023 05:36:27
%S 1,5,30,186,1276,9828,86279,866474,9924846,128592118,1864888539,
%T 29950693288,527584198445,10109318656565,209256249845854,
%U 4651751087878667,110501782280985273,2792991694461152344,74832356485576239136,2118333127408342718683,63169771935593153194107
%N The number of Feynman graphs in phi^3 theory with 2n vertices, 2 external legs.
%C a(n) is the number of multigraphs with 2n unlabeled nodes of degree 3 plus 2 noninterchangeable nodes of degree 1, loops allowed. - _Andrew Howroyd_, Mar 10 2023
%H R. de Mello Koch and S. Ramgoolam, <a href="https://doi.org/10.1103/PhysRevD.85.026007">Strings from Feynman graph counting: Without large N</a>, Phys. Rev. D 85 (2012) 026007, App. D.
%H R. J. Mathar, <a href="/A352175/a352175.pdf">Illustrations</a>
%Y Cf. A129427 (no external legs), A352173 (degree 4 case), A361447 (connected).
%K nonn
%O 0,2
%A _R. J. Mathar_, Mar 07 2022
%E a(0) prepended and terms a(9) and beyond from _Andrew Howroyd_, Mar 10 2023
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