%I A005226 M1563
%S A005226 0,1,1,2,6,6,27,20,130,124,598,641,4850
%N A005226 Number of atomic species of degree n; also number of connected permutation 
               groups of degree n.
%C A005226 An atomic species is one that is not the product of smaller species. 
               - Christian G. Bower (bowerc(AT)usa.net), Feb 23 2006
%C A005226 A permutation group is connected if it is not the direct product of smaller 
               permutation groups. - Christian G. Bower (bowerc(AT)usa.net), Feb 
               23 2006
%D A005226 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A005226 F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like 
               Structures, Camb. 1998, p. 147.
%D A005226 J. Labelle and Y. N. Yeh, The relation between Burnside rings and combinatorial 
               species, J. Combin. Theory, A 50 (1989), 269-284.
%H A005226 N. J. A. Sloane, <a href="transforms.txt">Transforms</a>
%F A005226 Inverse Euler transform of A000638. Define b(n), c(n): b(1)=c(0)=0. b(k)=A005227(k), 
               k>1. c(k)=A000638(k), k>0. a(n) is Dirichlet convolution of b and 
               c. - Christian G. Bower (bowerc(AT)usa.net), Feb 23 2006
%Y A005226 Cf. A005227. Unlabeled version of A116655.
%Y A005226 Sequence in context: A100634 A130865 A105725 this_sequence A087310 A130087 
               A085087
%Y A005226 Adjacent sequences: A005223 A005224 A005225 this_sequence A005227 A005228 
               A005229
%K A005226 nonn,hard
%O A005226 0,4
%A A005226 Simon Plouffe (simon.plouffe(AT)gmail.com)
%E A005226 a(11) corrected and a(12) added by Christian G. Bower (bowerc(AT)usa.net), 
               Feb 23 2006 based on Goetz Pfeiffer's edit to A000638.