cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-5 of 5 results.

A000638 Number of permutation groups of degree n; also number of conjugacy classes of subgroups of symmetric group S_n; also number of molecular species of degree n.

Original entry on oeis.org

1, 1, 2, 4, 11, 19, 56, 96, 296, 554, 1593, 3094, 10723, 20832, 75154, 159129, 686165, 1466358, 7274651
Offset: 0

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Author

Keywords

References

  • F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Camb. 1998, p. 147.
  • Labelle, Jacques. "Quelques espèces sur les ensembles de petite cardinalité.", Ann. Sc. Math. Québec 9.1 (1985): 31-58.
  • G. Pfeiffer, Counting Transitive Relations, preprint 2004.
  • C. C. Sims, Computational methods in the study of permutation groups, pp. 169-183 of J. Leech, editor, Computational Problems in Abstract Algebra. Pergamon, Oxford, 1970.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Partial sums of A000637.
Cf. A000001, A000019. Unlabeled version of A005432.

Programs

  • GAP
    # GAP 4.2
    Length(ConjugacyClassesSubgroups(SymmetricGroup(n)));
  • Magma
    n := 5; #SubgroupLattice(Sym(n));
    

Formula

Euler Transform of A005226. Define b(n), c(n), d(n): b(1)=d(1)=0. b(k)=A005227(k), k>1. c(k)=a(k), k>0, d(k)=A005226(k), k>1. d is Dirichlet convolution of b and c. - Christian G. Bower, Feb 23 2006

Extensions

a(11) corrected and a(12) added by Goetz Pfeiffer (goetz.pfeiffer(AT)nuigalway.ie), Jan 21 2004
Extended to a(18) using Derek Holt's data from A000637. - N. J. A. Sloane, Jul 31 2010

A000637 Number of fixed-point-free permutation groups of degree n.

Original entry on oeis.org

1, 0, 1, 2, 7, 8, 37, 40, 200, 258, 1039, 1501, 7629, 10109, 54322, 83975, 527036, 780193, 5808293
Offset: 0

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Keywords

Comments

a(1) = 0 since the trivial group of degree 1 has a fixed point. One could also argue that one should set a(1) = 1 by convention.

References

  • G. Butler and J. McKay, The transitive groups of degree up to eleven, Comm. Algebra, 11 (1983), 863-911.
  • D. Holt, Enumerating subgroups of the symmetric group. Computational Group Theory and the Theory of Groups, II, edited by L.-C. Kappe, A. Magidin and R. Morse. AMS Contemporary Mathematics book series, vol. 511, pp. 33-37.
  • A. Hulpke, Konstruktion transitiver Permutationsgruppen, Dissertation, RWTH Aachen, 1996.
  • A. Hulpke, Constructing transitive permutation groups, J. Symbolic Comput. 39 (2005), 1-30.
  • A. Hulpke, Constructing Transitive Permutation Groups, in preparation
  • C. C. Sims, Computational methods in the study of permutation groups, pp. 169-183 of J. Leech, editor, Computational Problems in Abstract Algebra. Pergamon, Oxford, 1970.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A000019, A002106. Unlabeled version of A116693.

Formula

a(n) = A000638(n) - A000638(n-1). - Christian G. Bower, Feb 23 2006

Extensions

More terms from Alexander Hulpke
a(2) and a(10) corrected, a(11) and a(12) added by Christian G. Bower, Feb 23 2006
Terms a(13)-a(18) were computed by Derek Holt and contributed by Alexander Hulpke, Jul 30 2010, who comments that he has verified the terms up through a(16).
Edited by N. J. A. Sloane, Jul 30 2010, at the suggestion of Michael Somos

A005227 Number of atomic species of degree n which are not nontrivial substitutions.

Original entry on oeis.org

0, 1, 1, 2, 4, 6, 19, 20, 111, 116, 567, 641, 4718, 4772, 35489, 46012, 389277, 487408, 4616580
Offset: 0

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Author

Keywords

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).

Crossrefs

Cf. A005226.

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

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
a(13)-a(18) from Vaclav Kotesovec, Jul 18 2022

A007650 Number of set-like atomic species of degree n.

Original entry on oeis.org

0, 1, 1, 1, 3, 1, 6, 1, 10, 4, 12, 1, 33, 1, 29, 13, 64, 1, 100, 1, 156, 30, 187, 1, 443, 10, 476, 78, 877, 1, 1326, 1, 2098, 188, 2745, 36, 5203, 1, 6408, 477, 11084, 1, 15687, 1, 24709, 1241, 33249, 1, 57432, 27, 74529, 2746, 120984, 1, 168668, 194, 264075, 6409, 356624, 1, 579893, 1, 768857, 14898, 1214452, 483, 1669060, 1
Offset: 0

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Author

Keywords

References

  • G. Labelle and P. Leroux, Identities and enumeration: weighting connected components, Abstracts Amer. Math. Soc., 15 (1994), Meeting #896.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Mathematica
    NN = 66;  va = Array[0&, NN]; va[[1]] = 0; va[[2]] = 1; vm = Array[0&, NN]; vm[[1]] = 1; vm[[2]] = 1; For[n = 2, n <= NN - 1, n++, va[[n + 1]] = DivisorSum[n , vm[[#+1]]&]; vm[[n+1]] = 1/n*Sum[DivisorSum[k, #*va[[#+1]] &]*vm[[n-k+1]], {k, 1, n}]]; va (* Jean-François Alcover, Dec 01 2015, adapted from Joerg Arndt's PARI script in A007649 *)
  • PARI
    /* see A007649 */

Formula

Inverse Euler Transform of A007649. Define c(n): c(0)=0. c(k)=A007649(k), k>0. a=MOEBIUSi(c)-c. - Christian G. Bower, Feb 23 2006

Extensions

Added more terms, Joerg Arndt, Jul 30 2012

A116655 Number of connected subgroups of the symmetric group S_n.

Original entry on oeis.org

0, 1, 1, 2, 12, 30, 639, 1835, 64601, 369518, 12351620, 78569754, 5477440592, 35108337731, 3031753084624, 30230571143624, 3308601182539217, 33507627807222128, 5183154493935250901
Offset: 0

Views

Author

Christian G. Bower, Feb 23 2006

Keywords

Crossrefs

Labeled version of A005226.

Formula

Logarithmic transform of A005432.

Extensions

a(13)-a(18) added (using data from A005432) by Alois P. Heinz, Dec 04 2018
Showing 1-5 of 5 results.