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

A057731 Irregular triangle read by rows: T(n,k) = number of elements of order k in symmetric group S_n, for 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, 2, 1, 9, 8, 6, 1, 25, 20, 30, 24, 20, 1, 75, 80, 180, 144, 240, 1, 231, 350, 840, 504, 1470, 720, 0, 0, 504, 0, 420, 1, 763, 1232, 5460, 1344, 10640, 5760, 5040, 0, 4032, 0, 3360, 0, 0, 2688, 1, 2619, 5768, 30996, 3024, 83160, 25920, 45360, 40320, 27216, 0, 30240, 0, 25920, 24192, 0, 0, 0, 0, 18144
Offset: 1

Views

Author

Roger Cuculière, Oct 29 2000

Keywords

Comments

Every row for n >= 7 contains zeros. Landau's function quickly becomes > 2*n, and there is always a prime between n and 2*n. T(n,p) = 0 for such a prime p. - Franklin T. Adams-Watters, Oct 25 2011

Examples

			Triangle begins:
  1;
  1,   1;
  1,   3,   2;
  1,   9,   8,   6;
  1,  25,  20,  30,  24,   20;
  1,  75,  80, 180, 144,  240;
  1, 231, 350, 840, 504, 1470, 720, 0, 0, 504, 0, 420;
  ...
		

References

  • Herbert S. Wilf, "The asymptotics of e^P(z) and the number of elements of each order in S_n." Bull. Amer. Math. Soc., 15.2 (1986), 225-232.

Crossrefs

Cf. A000793, also A054522 (for cyclic group), A057740 (alternating group), A057741 (dihedral group).
Rows sums give A000142, last elements of rows give A074859, columns k=2, 3, 5, 7, 11 give A001189, A001471, A059593, A153760, A153761. - Alois P. Heinz, Feb 16 2013
Main diagonal gives A074351.
Cf. A222029.

Programs

  • Magma
    {* Order(g) : g in Sym(6) *};
    
  • Maple
    with(group):
    for n from 1 do
        f := [seq(0,i=1..n!)] ;
        mknown := 0 ;
        # loop through the permutations of n
        Sn := combinat[permute](n) ;
        for per in Sn do
            # write this permutation in cycle notation
            gen := convert(per,disjcyc) ;
            # compute the list of lengths of the cycles, then the lcm of these
            cty := [seq(nops(op(i,gen)),i=1..nops(gen))] ;
            if cty <> [] then
                lcty := lcm(op(cty)) ;
            else
                lcty := 1 ;
            end if;
            f := subsop(lcty = op(lcty,f)+1,f) ;
            mknown := max(mknown,lcty) ;
        end do:
        ff := add(el,el=f) ;
        print(seq(f[i],i=1..mknown)) ;
    end do: # R. J. Mathar, May 26 2014
    # second Maple program:
    b:= proc(n, g) option remember; `if`(n=0, x^g, add((j-1)!
          *b(n-j, ilcm(g, j))*binomial(n-1, j-1), j=1..n))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=1..degree(p)))(b(n, 1)):
    seq(T(n), n=1..12);  # Alois P. Heinz, Jul 11 2017
  • Mathematica
    <Jean-François Alcover, Aug 31 2016 *)
    b[n_, g_] := b[n, g] = If[n == 0, x^g, Sum[(j-1)!*b[n-j, LCM[g, j]]* Binomial[n-1, j-1], {j, 1, n}]];
    T[n_] := Function[p, Table[Coefficient[p, x, i], {i, 1, Exponent[p, x]}]][ b[n, 1]];
    Array[T, 12] // Flatten (* Jean-François Alcover, May 03 2019, after Alois P. Heinz *)
  • PARI
    T(n,k)={n!*polcoeff(sumdiv(k, i, moebius(k/i)*exp(sumdiv(i, j, x^j/j) + O(x*x^n))), n)} \\ Andrew Howroyd, Jul 02 2018

Formula

Sum_{k=1..A000793(n)} k*T(n,k) = A060014(n); A000793 = Landau's function.

Extensions

More terms from N. J. A. Sloane, Nov 01 2000

A048099 Number of degree-n even permutations of order exactly 2.

Original entry on oeis.org

0, 0, 0, 3, 15, 45, 105, 315, 1323, 5355, 18315, 63855, 272415, 1264263, 5409495, 22302735, 101343375, 507711375, 2495918223, 11798364735, 58074029055, 309240315615, 1670570920095, 8792390355903, 46886941456575, 264381946998975, 1533013006902975, 8785301059346175, 50439885753378303
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A001189, A051695. A column of A057740.

Programs

  • Mathematica
    Table[Sum[Binomial[n , 4 i] (4 i)!/(2^(2 i) (2 i)!), {i, 1, Floor[n/4]}], {n,1,22}] (* Luis Manuel Rivera Martínez, May 16 2018 *)
  • PARI
    a(n) = sum(i=1, n\4, binomial(n,4*i)*(4*i)!/(2^(2*i)*(2*i)!)); \\ Michel Marcus, May 17 2018
    
  • PARI
    seq(n)={my(A=O(x*x^n)); Vec(serlaplace(exp(x + x^2/2 + A) + exp(x - x^2/2 + A) - 2*exp(x + A))/2, -n)} \\ Andrew Howroyd, Feb 01 2020

Formula

a(n) = (A001189(n) + A051684(n))/2.
a(n) = Sum_{i=1..floor(n/4)} binomial(n,4i)(4i)!/(2^(2i)(2i)!). - Luis Manuel Rivera Martínez, May 16 2018
E.g.f.: (exp(x + x^2/2) + exp(x - x^2/2))/2 - exp(x). - Andrew Howroyd, Feb 01 2020

A051593 Largest order of even permutation of n elements, or maximal order of element of alternating group A_n.

Original entry on oeis.org

1, 1, 1, 3, 3, 5, 5, 7, 15, 15, 21, 21, 35, 35, 60, 105, 105, 105, 140, 210, 210, 420, 420, 420, 420, 840, 1155, 1260, 1365, 1540, 2310, 2520, 4620, 4620, 5460, 5460, 9240, 9240, 13860, 15015, 16380, 16380, 27720, 30030, 32760, 60060, 60060, 60060
Offset: 0

Views

Author

Keywords

References

  • J. H. Conway, R. T. Curtis, S. P. Norton, R. A. Parker and R. A. Wilson, ATLAS of Finite Groups. Oxford Univ. Press, 1985 [for best online version see https://oeis.org/wiki/Welcome#Links_to_Other_Sites].
  • V. Jovovic, Some combinatorial characteristics of symmetric and alternating groups (in Russian), Belgrade, 1980, unpublished.

Crossrefs

Programs

  • Mathematica
    (* a3 = A000793  a4 = A051704 *) a3[n_] := Max[LCM @@@ IntegerPartitions[n]]; a4[n_] := (pp = Reap[ Do[ pk = p^k; If[pk <= n, Sow[pk]], {p, Prime[ Range[2, PrimePi[n]]]}, {k, 1, Ceiling[ Log[3, n]]}]][[2, 1]]; sel = Select[ IntegerPartitions[n, All, pp], Length[#] == Length[ Union[#] && !MatchQ[#, {_, x_, _, y_, _} /; GCD[x, y] != 1]] &]; Max[Times @@@ sel]); a4[0] = 1; a4[1] = a4[2] = a4[4] = a4[6] = 0; a[n_] := Max[a3[n - 2], a4[n - 1], a4[n]]; a[0] = a[1] = a[2] = 1; Table[a[n], {n, 0, 47}] (* Jean-François Alcover, Sep 11 2012, from formula *)
  • PARI
    a(n)={my(m=1); forpart(p=n, if(sum(i=1, #p, p[i]-1)%2==0, m=max(m, lcm(Vec(p))))); m} \\ Andrew Howroyd, Jul 03 2018

Formula

a(n)=max{ A000793(n-2), A051704(n-1), A051704(n) }, a(0)=a(1)=1.

A057741 Table T(n,k) giving number of elements of order k in dihedral group D_{2n} of order 2n, n >= 1, 1<=k<=g(n), where g(n) = 2 if n=1 else g(n) = n.

Original entry on oeis.org

1, 1, 1, 3, 1, 3, 2, 1, 5, 0, 2, 1, 5, 0, 0, 4, 1, 7, 2, 0, 0, 2, 1, 7, 0, 0, 0, 0, 6, 1, 9, 0, 2, 0, 0, 0, 4, 1, 9, 2, 0, 0, 0, 0, 0, 6, 1, 11, 0, 0, 4, 0, 0, 0, 0, 4, 1, 11, 0, 0, 0, 0, 0, 0, 0, 0, 10, 1, 13, 2, 2, 0, 2, 0, 0, 0, 0, 0, 4, 1, 13, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 12, 1, 15, 0, 0, 0, 0, 6, 0, 0
Offset: 1

Views

Author

Roger Cuculière, Oct 29 2000

Keywords

Comments

Note that D_2 equals the cyclic group of order 2.

Examples

			1,1;
1,3;
1,3,2;
1,5,0,2;
1,5,0,0,4; ...
		

Crossrefs

Programs

  • Mathematica
    t[n_, k_] /; k != 2 && ! Divisible[n, k] = 0; t[n_, k_] /; k != 2 && Divisible[n, k] := EulerPhi[k]; t[n_, 2] := n + 1 - Mod[n, 2]; Flatten[Table[t[n, k], {n, 1, 14}, {k, 1, If[n == 1, 2, n]}]] (* Jean-François Alcover, Jun 19 2012, from formula *)
    row[n_] := (orders = PermutationOrder /@ GroupElements[DihedralGroup[n]]; Table[Count[orders, k], {k, 1, Max[orders]}]); Table[row[n], {n, 1, 14}] // Flatten (* Jean-François Alcover, Aug 31 2016 *)

Formula

If k<>2 and k does not divide n, this number is 0; if k<>2 and k divides n, this number is phi(k), where phi is the Euler totient function; if k=2, this number is n for odd n and n+1 for even n.

Extensions

More terms from James Sellers, Oct 30 2000

A145437 a(n) = number of elements of order n in simple group Alt(12) of order 239500800.

Original entry on oeis.org

1, 63855, 776600, 3825360, 4809024, 25530120, 570240, 29937600, 26611200, 25945920, 43545600, 21621600, 0, 8553600, 6652800, 0, 0, 0, 0, 11975040, 11404800, 0, 0, 0, 0, 0, 0, 0, 0, 3991680, 0, 0, 0, 0, 13685760
Offset: 1

Views

Author

N. J. A. Sloane, Apr 06 2009

Keywords

Crossrefs

A row of A057740. Cf. A031963.

Programs

  • Magma
    t1:=[0 : n in [1..240]];
    G:=Alt(12);
    t2:=Classes(G);
    for c in t2 do
    t1[c[1]] := t1[c[1]] + c[2];
    end for;
    t1;

A145822 a(n) = number of elements of order n in simple group Alt(11) of order 19958400.

Original entry on oeis.org

1, 18315, 142010, 457380, 809424, 2044350, 237600, 2494800, 2217600, 498960, 3628800, 2910600, 0, 712800, 887040, 0, 0, 0, 0, 997920, 1900800
Offset: 1

Views

Author

N. J. A. Sloane, Apr 06 2009

Keywords

Crossrefs

A row of A057740. Cf. A031963.

A102578 a(n) = number of elements of order n in simple group Alt(6) = L_2(9) of order 360.

Original entry on oeis.org

1, 45, 80, 90, 144
Offset: 1

Views

Author

N. J. A. Sloane, Apr 06 2009

Keywords

Crossrefs

Cf. A031963. A row of A057740.

A145752 a(n) = number of elements of order n in simple group Alt(7) of order 2520.

Original entry on oeis.org

1, 105, 350, 630, 504, 210, 720
Offset: 1

Views

Author

N. J. A. Sloane, Apr 06 2009

Keywords

Crossrefs

A row of A057740. Cf. A031963.

A145753 a(n) = number of elements of order n in simple group Alt(8) of order 20160.

Original entry on oeis.org

1, 315, 1232, 3780, 1344, 5040, 5760, 0, 0, 0, 0, 0, 0, 0, 2688
Offset: 1

Views

Author

N. J. A. Sloane, Apr 06 2009

Keywords

Crossrefs

A row of A057740. Cf. A031963.

A145754 a(n) = number of elements of order n in simple group Alt(9) of order 181440.

Original entry on oeis.org

1, 1323, 5768, 18900, 3024, 37800, 25920, 0, 40320, 9072, 0, 15120, 0, 0, 24192
Offset: 1

Views

Author

N. J. A. Sloane, Apr 06 2009

Keywords

Crossrefs

A row of A057740. Cf. A031963.
Showing 1-10 of 11 results. Next