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 1-10 of 11 results. Next

A009490 Number of distinct orders of permutations of n objects; number of nonisomorphic cyclic subgroups of symmetric group S_n.

Original entry on oeis.org

1, 1, 2, 3, 4, 6, 6, 9, 11, 14, 16, 20, 23, 27, 31, 35, 43, 47, 55, 61, 70, 78, 88, 98, 111, 123, 136, 152, 168, 187, 204, 225, 248, 271, 296, 325, 356, 387, 418, 455, 495, 537, 581, 629, 678, 732, 787, 851, 918, 986, 1056, 1133, 1217, 1307, 1399, 1498, 1600, 1708, 1823
Offset: 0

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Author

Keywords

Comments

Also number of different LCM's of partitions of n.
a(n) <= A023893(n), which counts the nonisomorphic Abelian subgroups of S_n. - M. F. Hasler, May 24 2013

Crossrefs

Cf. A051613 (first differences), A000792, A000793, A034891, A051625 (all cyclic subgroups), A256067.

Programs

  • Maple
    b:= proc(n,i) option remember; local p;
          p:= `if`(i<1, 1, ithprime(i));
          `if`(n=0 or i<1, 1, b(n, i-1)+
          add(b(n-p^j, i-1), j=1..ilog[p](n)))
        end:
    a:= n-> b(n, numtheory[pi](n)):
    seq(a(n), n=0..100);  # Alois P. Heinz, Feb 15 2013
  • Mathematica
    Table[ Length[ Union[ Apply[ LCM, Partitions[ n ], 1 ] ] ], {n, 30} ]
    f[n_] := Length@ Union[LCM @@@ IntegerPartitions@ n]; Array[f, 60, 0]
    (* Caution, the following is Extremely Slow and Resource Intensive *) CoefficientList[ Series[ Expand[ Product[1 + Sum[x^(Prime@ i^k), {k, 4}], {i, 10}]/(1 - x)], {x, 0, 30}], x]
    b[n_, i_] := b[n, i] = Module[{p}, p = If[i<1, 1, Prime[i]]; If[n == 0 || i<1, 1, b[n, i-1]+Sum[b[n-p^j, i-1], {j, 1, Log[p, n]}]]]; a[n_] := b[n, PrimePi[n]]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Feb 03 2014, after Alois P. Heinz *)
  • PARI
    /* compute David W. Wilson's g.f., needs <1 sec for 1000 terms */
    N=1000;  x='x+O('x^N); /* N terms */
    gf=1; /* generating function */
    { forprime(p=2,N,
        sm = 1;  pp=p;  /* sum;  prime power */
        while ( ppJoerg Arndt, Jan 19 2011 */

Formula

a(n) = Sum_{k=0..n} b(k), where b(k) is the number of partitions of k into distinct prime power parts (1 excluded) (A051613). - Vladeta Jovovic
G.f.: (Product_{p prime} (1 + Sum_{k >= 1} x^(p^k))) / (1-x). - David W. Wilson, Apr 19 2000

A051636 Number of "labeled" cyclic subgroups of alternating group A_n.

Original entry on oeis.org

1, 1, 2, 8, 32, 167, 947, 6974, 53426, 454682, 4303532, 50366912, 553031624, 6760260236, 90333982832, 1369522152392, 20986020606632, 350528387240264, 5751957395258096, 111685506968916032, 2139383543480892032, 41770889787378732752, 869742098042083451264
Offset: 1

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Author

Keywords

Crossrefs

Row sums of A303728.

Programs

  • Maple
    b:= proc(n, i, m, t) option remember; `if`(n=0, (1+(-1)^t)/numtheory
          [phi](m), add(1/j!/i^j*b(n-i*j, i-1, ilcm(m, `if`(j=0, 1, i)),
           irem(t+j*irem(i+1, 2), 2)), j=`if`(i=1, n, 0..n/i)))
        end:
    a:= n-> n!*b(n$2, 1, 0)/2:
    seq(a(n), n=1..25);  # Alois P. Heinz, Jul 03 2018
  • Mathematica
    f[list_] :=Total[list]!/(Apply[Times, list]*Apply[Times, Map[Length, Split[list]]!])/EulerPhi[Apply[LCM, list]]; Table[Total[Map[f,
       Select[IntegerPartitions[n],EvenQ[Length[Select[#, EvenQ[#] &]]] &]]], {n, 1, 21}] (* Geoffrey Critzer, Oct 03 2015 *)
    b[n_, i_, m_, t_] := b[n, i, m, t] = If[n == 0, (1 + (-1)^t)/
         EulerPhi[m], If[i == 0, 0, Sum[1/j!/i^j*b[n - i*j, i - 1, LCM[m,
         If[j == 0, 1, i]], Mod[t+j*Mod[i+1, 2], 2]], {j, Range[0, n/i]}]]];
    a[n_] := n! b[n, n, 1, 0]/2;
    Array[a, 25] (* Jean-François Alcover, Jun 04 2021, after Alois P. Heinz *)
  • PARI
    \\ permcount is number of permutations of given type.
    permcount(v) = {my(m=1,s=0,k=0,t); for(i=1,#v,t=v[i]; k=if(i>1&&t==v[i-1],k+1,1); m*=t*k;s+=t); s!/m}
    a(n)={my(s=0); forpart(p=n, if(sum(i=1, #p, p[i]-1)%2==0, s+=permcount(p) / eulerphi(lcm(Vec(p))))); s} \\ Andrew Howroyd, Jul 03 2018

Formula

a(n) = 1/2*Sum_{pi} (1+(-1)^(k_2+k_4+...)) * n!/(k_1!*1^k_1*k_2!*2^k_2*...*k_n!*n^k_n*phi(lcm{i:k_i != 0})), where pi runs through all partitions k_1+2*k_2+...+n*k_n=n and phi is Euler's function.

A074881 Triangle T(n,k) giving number of labeled cyclic subgroups of order k in symmetric group S_n, n >= 1, 1 <= k <= g(n), where g(n) = A000793(n) is Landau's function.

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 9, 4, 3, 1, 25, 10, 15, 6, 10, 1, 75, 40, 90, 36, 120, 1, 231, 175, 420, 126, 735, 120, 126, 105, 1, 763, 616, 2730, 336, 5320, 960, 1260, 1008, 840, 336, 1, 2619, 2884, 15498, 756, 41580, 4320, 11340, 6720, 6804, 7560, 4320, 3024, 2268
Offset: 1

Views

Author

Vladeta Jovovic, Sep 30 2002

Keywords

Comments

A057731 contains zeros. This sequence contains only positive values of A057731(n,k)/A000010(k). - Alois P. Heinz, Feb 16 2013

Examples

			Triangle begins:
  1;
  1,   1;
  1,   3,   1;
  1,   9,   4,   3;
  1,  25,  10,  15,   6,  10;
  1,  75,  40,  90,  36, 120;
  1, 231, 175, 420, 126, 735, 120, 126, 105;
  ...
		

Crossrefs

Row sums give A051625.

Programs

  • Mathematica
    nmax = 10;
    T[n_, k_] := n! SeriesCoefficient[O[x]^(n+1) + Sum[MoebiusMu[k/i]*Exp[ Sum[x^j/j, {j, Divisors[i]}]], {i, Divisors[k]}], {x, 0, n}]/ EulerPhi[k];
    Table[DeleteCases[Table[T[n, k], {k, 1, 2 nmax}], 0], {n, 1, nmax}] // Flatten (* Jean-François Alcover, Sep 16 2019, after Andrew Howroyd *)
  • PARI
    T(n,k)={n!*polcoeff(sumdiv(k, i, moebius(k/i)*exp(sumdiv(i, j, x^j/j) + O(x*x^n))), n)/eulerphi(k)} \\ Andrew Howroyd, Jul 02 2018

Formula

T(n,k) = A057731(n,k)/A000010(k).

A063182 Number of cyclic subgroups of the group S_n X S_n (where S_n is the symmetric group of degree n).

Original entry on oeis.org

1, 4, 26, 314, 5222, 168632, 5736908, 291993032, 18599068328, 1547379999392, 136254185631632, 18749419634845088, 2367416741670079712, 387737484226037810048, 78779133220155242489792, 17651532033334188604514432, 3945247307615376458903485568
Offset: 1

Views

Author

Vladeta Jovovic, Jul 10 2001

Keywords

Crossrefs

Cf. A051625, A060648, (unlabeled case) A063183.

Extensions

a(9)-a(17) from Stephen A. Silver, Feb 22 2013

A074260 Number of labeled cyclic subgroups of S_n having the maximum possible order.

Original entry on oeis.org

1, 1, 1, 1, 3, 10, 120, 105, 336, 2268, 15120, 332640, 498960, 6486480, 43243200, 259459200, 3113510400, 35286451200, 1270312243200, 3016991577600, 60339831552000, 1267136462592000, 37169336236032000, 160292762517888000
Offset: 0

Views

Author

Vladeta Jovovic, Sep 20 2002

Keywords

Crossrefs

Formula

a(n) = A074859(n)/A000010(A000793(n)).

A181949 Weighted sum of all cyclic subgroups of the Symmetric Group.

Original entry on oeis.org

1, 3, 10, 43, 231, 1531, 11068, 89895, 820543, 8484871, 95647476, 1186289083, 15648402355, 221728356123, 3354790995676, 53999879550991, 936289020367263, 17163114699673615, 328827078340587148, 6630244432204704771, 139769193881466850051, 3092293682224076627683
Offset: 1

Views

Author

Olivier Gérard, Apr 03 2012

Keywords

Comments

Sum of the orders of all cyclic subgroups of the Sym_n.
The identity permutation is counted for each subgroup, i.e. A051625(n) times.
Each permutation is counted several times according to its conjugacy class.

Examples

			a(4) = 1*1 + 2*3 + 2*6 + 3*4 + 4*3 = 1+6+12+12+12 = 43.
		

Crossrefs

Formula

a(n) = Sum_{k=1..A000793(n)} k*A074881(n, k). - Andrew Howroyd, Jul 02 2018

Extensions

a(9)-a(22) from Andrew Howroyd, Jul 02 2018

A218958 Total number of maximal cyclic subgroups of the symmetric group, counting conjugates as distinct.

Original entry on oeis.org

1, 1, 1, 4, 13, 31, 246, 1296, 10774, 83238, 788820, 6835170, 81364944, 848378532, 11423650616, 156289508025, 2380629720720, 33284133330760, 605934954285120, 9708364832948820, 190330953679235040, 3715069138923234960, 77101583995105472880, 1506549946554254503440
Offset: 0

Views

Author

Liam Naughton, Nov 23 2012

Keywords

Crossrefs

Programs

  • PARI
    \\ See links for program script file.
    a(n)=MaximalCyclicSubgroupCount(n, v->1); \\ Andrew Howroyd, Jul 17 2018

Extensions

Terms a(14) and beyond from Andrew Howroyd, Jul 03 2018

A062297 Number of distinct Abelian subgroups of the symmetric group S_n.

Original entry on oeis.org

1, 2, 5, 21, 87, 612, 3649, 35515, 289927, 377118, 36947363, 657510251, 7736272845
Offset: 1

Views

Author

Ahmed Fares (ahmedfares(AT)my-deja.com), Jul 02 2001

Keywords

Crossrefs

Programs

  • GAP
    # GAP 4.4
    LoadPackage("sonata");;
    for n in [2,3,4,5,6,7,8,9,10] do
        p := SymmetricGroup(n) ;;
        o := Order(p);
        s := Subgroups(p);
        f := Filtered(s, g -> IsAbelian(g));
        a := Size(f);
        Print(a," ") ;
    od; # R. J. Mathar, May 24 2013

Extensions

a(9)-a(13) added by Liam Naughton

A074880 Number of labeled cyclic subgroups of S_n having order n.

Original entry on oeis.org

1, 1, 1, 3, 6, 120, 120, 1260, 6720, 128520, 362880, 20041560, 39916800, 1132971840, 11721790080, 163459296000, 1307674368000, 87307501881600, 355687428096000, 19137704006453760, 205947392645030400, 5118231678995635200, 51090942171709440000, 4769913628444053196800
Offset: 1

Views

Author

Vladeta Jovovic, Sep 30 2002

Keywords

Crossrefs

Programs

  • PARI
    a(n)={n!*polcoeff(sumdiv(n, i, moebius(n/i)*exp(sumdiv(i, j, x^j/j) + O(x*x^n))), n)/eulerphi(n)} \\ Andrew Howroyd, Jul 02 2018

Formula

a(n) = A074351(n)/A000010(n).

Extensions

Terms a(22) and beyond from Andrew Howroyd, Jul 02 2018

A226142 The smallest positive integer k such that the symmetric group S_n is a product of k cyclic groups.

Original entry on oeis.org

1, 1, 2, 3, 3, 4, 4
Offset: 1

Views

Author

W. Edwin Clark, May 27 2013

Keywords

Comments

Since S_{n+1} is a product of a subgroup isomorphic to S_n and the cyclic group <(1,2,3,...,n+1)> we have a(n+1) <= a(n) + 1. On the other hand it is not clear that a(n) <= a(n+1) for all n. A lower bound is given by A226143(n) = ceiling(log(m)(n!)), m = A000793(n), a sequence that is not nondecreasing.
This sequence was suggested by a posting of L. Edson Jeffery on the seqfans mailing list on May 24, 2013.
Cardinality of the smallest subset(s) X of S_n such that every permutation in S_n can be expressed as a product of some elements in X. - Joerg Arndt, Dec 13 2015

Examples

			a(7) = 4 since a factorization of S_7 is given by C_1*C_2*C_3*C_4 where
C_1 = <(1,2,3,4)(5,6,7)>,
C_2 = <(1,4,6)(2,3,5,7)>,
C_3 = <(1,2,5,7)(3,4,6)>,
C_4 = <(1,3,5,6,7)(2,4)>,
and a brute force computation shows that S_7 is not a product of 3 or fewer cyclic subgroups.
		

Crossrefs

Showing 1-10 of 11 results. Next