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 A174511 The number of isomorphism classes of subgroups of the symmetric group S_n. 2
 1, 2, 4, 9, 16, 29, 55, 137, 241, 453, 894, 2065, 3845 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Two subgroups are considered to be isomorphic here if they are isomorphic as abstract groups, not as permutation groups. - N. J. A. Sloane, Nov 28 2010 LINKS A. Distler and T. Kelsey, The semigroups of order 9 and their automorphism groups, arXiv preprint arXiv:1301.6023, 2013. - From N. J. A. Sloane, Feb 19 2013 EXAMPLE a(3) = 4 since S_3 contains up to isomorphism exactly one subgroup of each of the orders 1,2,3,6. PROG (GAP) a:=[]; for n in [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] do G:=SymmetricGroup(n); R:=ConjugacyClassesSubgroups(G); RR:=ListX(R, Representative); T:=[RR[1]]; for g in RR do flag:=false; for h in T do if IsomorphismGroups(g, h)<>fail then flag:=true; break; fi; od; if flag=false then Add(T, g); fi; od; Add(a, Size(T)); od; Print(a, "\n"); CROSSREFS Cf. A000638, A005432. Sequence in context: A000291 A081055 A034446 * A034452 A034449 A082894 Adjacent sequences: A174508 A174509 A174510 * A174512 A174513 A174514 KEYWORD nonn,more AUTHOR W. Edwin Clark, Nov 28 2010 EXTENSIONS a(11) and a(12) from Stephen A. Silver, Feb 24 2013 a(13) (as calculated by Jack Schmidt) from L. Edson Jeffery, May 26 2013 STATUS approved

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Last modified February 4 11:35 EST 2023. Contains 360055 sequences. (Running on oeis4.)