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 A005227 Number of atomic species of degree n which are not nontrivial substitutions. (Formerly M1029) 2
 0, 1, 1, 2, 4, 6, 19, 20, 111, 116, 567, 641, 4718 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 REFERENCES Labelle, Jacques. Quelques espèces sur les ensembles de petite cardinalité, Ann. Sc. Math. Québec 9.1 (1985): 31-58. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS H. Decoste, G. Labelle, & J. Labelle, Espèces sur les petites cardinalités Tableaux divers, Université du Québec à Montréal (octobre 1988), Unpublished. Jacques Labelle, Quelques espèces sur les ensembles de petite cardinalité, Ann. Sc. Math. Québec 9.1 (1985): 31-58. (Annotated scanned copy of preprint) J. Labelle and Y. N. Yeh, The relation between Burnside rings and combinatorial species, J. Combin. Theory, A 50 (1989), 269-284. FORMULA Define b(n), c(n), d(n): b(1)=d(1)=0. b(k)=a(k), k>1. c(k)=A000638(k), k>0, d(k)=A005226(k), k>1. d is Dirichlet convolution of b and c. - Christian G. Bower, Feb 23 2006 CROSSREFS Cf. A005226. Sequence in context: A294447 A143085 A304756 * A185185 A234019 A279188 Adjacent sequences:  A005224 A005225 A005226 * A005228 A005229 A005230 KEYWORD nonn,hard,more AUTHOR EXTENSIONS a(8), a(11) corrected and a(12) added by Christian G. Bower, Feb 23 2006 based on Goetz Pfeiffer's edit to A000638. STATUS approved

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Last modified October 1 17:45 EDT 2020. Contains 337444 sequences. (Running on oeis4.)