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 A005415 Tensors with n external gluons. (Formerly M2080) 1
 1, 0, 1, 2, 15, 140, 1915, 33810, 734545, 18929960, 564216345, 19088149850, 722508543295, 30249199720740, 1387823333771875, 69238799231051450, 3731906171773805025, 216101966957781304400, 13379538319131196637425, 881962125004262056604850 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS See Fig. 26, p. 1549 in the Cvitanovic reference. - Jonathan Vos Post, Feb 20 2010 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Alois P. Heinz, Table of n, a(n) for n = 0..368 P. Cvitanovic, Group theory for Feynman diagrams in non-Abelian gauge theories, Phys. Rev. D14 (1976), 1536-1553. FORMULA a(n) = Sum_{k=0..n-1} binomial(n-1, k) * a(k) * b(n-k) where b(1) = 0, b(2) = 1, b(n) = 2^(n-2) * (2*n-5)!! = A001813(n-2) [From Cvitanovic]. - Sean A. Irvine, Jun 17 2016 CROSSREFS Cf. A001813. Sequence in context: A215922 A285449 A288950 * A219868 A224885 A253571 Adjacent sequences:  A005412 A005413 A005414 * A005416 A005417 A005418 KEYWORD nonn,nice AUTHOR EXTENSIONS More terms from Sean A. Irvine, Jun 17 2016 STATUS approved

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Last modified February 21 03:06 EST 2019. Contains 320364 sequences. (Running on oeis4.)