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.

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A008307 Table T(n,k) giving number of permutations of [1..n] with order dividing k, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 4, 1, 1, 1, 10, 3, 2, 1, 1, 26, 9, 4, 1, 1, 1, 76, 21, 16, 1, 2, 1, 1, 232, 81, 56, 1, 6, 1, 1, 1, 764, 351, 256, 25, 18, 1, 2, 1, 1, 2620, 1233, 1072, 145, 66, 1, 4, 1, 1, 1, 9496, 5769, 6224, 505, 396, 1, 16, 3, 2, 1, 1, 35696, 31041, 33616, 1345, 2052, 1, 56, 9, 4, 1, 1
Offset: 1

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Author

Keywords

Comments

Solutions to x^k = 1 in Symm_n (the symmetric group of degree n).

Examples

			Array begins:
  1,   1,    1,    1,    1,     1,    1,     1, ...
  1,   2,    1,    2,    1,     2,    1,     2, ...
  1,   4,    3,    4,    1,     6,    1,     4, ...
  1,  10,    9,   16,    1,    18,    1,    16, ...
  1,  26,   21,   56,   25,    66,    1,    56, ...
  1,  76,   81,  256,  145,   396,    1,   256, ...
  1, 232,  351, 1072,  505,  2052,  721,  1072, ...
  1, 764, 1233, 6224, 1345, 12636, 5761, 11264, ...
		

References

  • L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 257.
  • J. D. Dixon, B. Mortimer, Permutation Groups, Springer (1996), Exercise 1.2.13.

Crossrefs

Programs

  • Maple
    A:= proc(n,k) option remember; `if`(n<0, 0, `if`(n=0, 1,
           add(mul(n-i, i=1..j-1)*A(n-j,k), j=numtheory[divisors](k))))
        end:
    seq(seq(A(1+d-k, k), k=1..d), d=1..12); # Alois P. Heinz, Feb 14 2013
    # alternative
    A008307 := proc(n,m)
        local x,d ;
        add(x^d/d, d=numtheory[divisors](m)) ;
        exp(%) ;
        coeftayl(%,x=0,n) ;
        %*n! ;
    end proc:
    seq(seq(A008307(1+d-k,k),k=1..d),d=1..12) ; # R. J. Mathar, Apr 30 2017
  • Mathematica
    t[n_ /; n >= 0, k_ /; k >= 0] := t[n, k] = Sum[(n!/(n - d + 1)!)*t[n - d, k], {d, Divisors[k]}]; t[, ] = 1; Flatten[ Table[ t[n - k, k], {n, 0, 12}, {k, 1, n}]] (* Jean-François Alcover, Dec 12 2011, after given formula *)

Formula

T(n+1,k) = Sum_{d|k} (n)_(d-1)*T(n-d+1,k), where (n)_i = n!/(n - i)! = n*(n - 1)*(n - 2)*...*(n - i + 1) is the falling factorial.
E.g.f. for n-th row: Sum_{n>=0} T(n,k)*t^n/n! = exp(Sum_{d|k} t^d/d).

Extensions

More terms from Vladeta Jovovic, Apr 13 2001

A005388 Number of degree-n permutations of order a power of 2.

Original entry on oeis.org

1, 1, 2, 4, 16, 56, 256, 1072, 11264, 78976, 672256, 4653056, 49810432, 433429504, 4448608256, 39221579776, 1914926104576, 29475151020032, 501759779405824, 6238907914387456, 120652091860975616, 1751735807564578816, 29062253310781161472, 398033706586943258624
Offset: 0

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Author

Keywords

Comments

Differs from A053503 first at n=32. - Alois P. Heinz, Feb 14 2013

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Example 5.2.10.

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 40);
    f:= func< x | Exp( (&+[x^(2^j)/2^j: j in [0..14]]) ) >;
    Coefficients(R!(Laplace( f(x) ))); // G. C. Greubel, Nov 17 2022
    
  • Maple
    a:= proc(n) option remember; `if`(n<0, 0, `if`(n=0, 1,
           add(mul(n-i, i=1..2^j-1)*a(n-2^j), j=0..ilog2(n))))
        end:
    seq(a(n), n=0..25);  # Alois P. Heinz, Feb 14 2013
  • Mathematica
    max = 23; CoefficientList[ Series[ Exp[ Sum[x^2^m/2^m, {m, 0, max}]], {x, 0, max}], x]*Range[0, max]! (* Jean-François Alcover, Sep 10 2013 *)
  • SageMath
    def f(x): return exp(sum(x^(2^j)/2^j for j in range(15)))
    def A005388_list(prec):
        P. = PowerSeriesRing(QQ, prec)
        return P( f(x) ).egf_to_ogf().list()
    A005388_list(40) # G. C. Greubel, Nov 17 2022

Formula

E.g.f.: exp(Sum_{m>=0} x^(2^m)/2^m).
E.g.f.: 1/Product_{k>=1} (1 - x^(2*k-1))^(mu(2*k-1)/(2*k-1)), where mu() is the Moebius function. - Seiichi Manyama, Jul 06 2024

A061132 Number of degree-n even permutations of order dividing 10.

Original entry on oeis.org

1, 1, 1, 1, 4, 40, 190, 610, 1660, 13420, 174700, 1326700, 30818800, 342140800, 2534931400, 16519411000, 143752426000, 4842417082000, 73620307162000, 687934401562000, 17165461784680000, 308493094924720000, 4585953613991980000, 53843602355379220000
Offset: 0

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Author

Vladeta Jovovic, Apr 14 2001

Keywords

Examples

			For n=4 the a(4)=4 solutions are (1), (1, 2)(3, 4), (1, 3)(2, 4), (1, 4)(2, 3) (permutations in cyclic notation). - _Luis Manuel Rivera Martínez_, Jun 18 2019
		

References

  • J. Riordan, An Introduction to Combinatorial Analysis, John Wiley & Sons, Inc. New York, 1958 (Chap 4, Problem 22).

Crossrefs

Programs

  • Mathematica
    With[{nn = 22}, CoefficientList[Series[1/2 Exp[x + x^2/2 + x^5/5 + x^10/10] + 1/2 Exp[x - x^2/2 + x^5/5 - x^10/10], {x, 0, nn}], x]* Range[0, nn]!] (* Luis Manuel Rivera Martínez, Jun 18 2019 *)
  • PARI
    my(x='x+O('x^25)); Vec(serlaplace(1/2*exp(x + 1/2*x^2 + 1/5*x^5 + 1/10*x^10) + 1/2*exp(x - 1/2*x^2 + 1/5*x^5 - 1/10*x^10))) \\ Michel Marcus, Jun 18 2019

Formula

E.g.f.: 1/2*exp(x + 1/2*x^2 + 1/5*x^5 + 1/10*x^10) + 1/2*exp(x - 1/2*x^2 + 1/5*x^5 - 1/10*x^10).

A061133 Number of degree-n even permutations of order exactly 6.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 210, 5040, 37800, 201600, 2044350, 25530120, 213993780, 1692490800, 19767998250, 232823791200, 2235629476080, 23171222430720, 294649445112750, 4300403589581400, 55176842335916700, 660577269463243440
Offset: 1

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Author

Vladeta Jovovic, Apr 14 2001

Keywords

Crossrefs

Formula

E.g.f.: exp(x) - 1/2*exp(x + 1/2*x^2) - 1/2*exp(x - 1/2*x^2) - exp(x + 1/3*x^3) + 1/2*exp(x + 1/2*x^2 + 1/3*x^3 + 1/6*x^6) + 1/2*exp(x - 1/2*x^2 + 1/3*x^3 - 1/6*x^6).

A061135 Number of degree-n even permutations of order exactly 10.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 9072, 90720, 498960, 25945920, 321080760, 2460970512, 14552417880, 115251776640, 4603779180000, 72193873752000, 681167139805152, 16976210865344640, 304992335584165320, 4548189212204243760
Offset: 1

Views

Author

Vladeta Jovovic, Apr 14 2001

Keywords

Crossrefs

Formula

E.g.f.: exp(x) - 1/2*exp(x + 1/2*x^2) - 1/2*exp(x - 1/2*x^2) - exp(x + 1/5*x^5) + 1/2*exp(x + 1/2*x^2 + 1/5*x^5 + 1/10*x^10) + 1/2*exp(x - 1/2*x^2 + 1/5*x^5 - 1/10*x^10).

A061129 Number of degree-n even permutations of order dividing 4.

Original entry on oeis.org

1, 1, 1, 1, 4, 16, 136, 736, 4096, 20224, 99856, 475696, 3889216, 31778176, 313696384, 2709911296, 23006784256, 179965340416, 1532217039616, 13081112406784, 147235213351936, 1657791879049216, 20132199908571136, 226466449808367616, 2542933338768769024
Offset: 0

Views

Author

Vladeta Jovovic, Apr 14 2001

Keywords

Crossrefs

Programs

  • Magma
    m:=30; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!( Exp(x)*Cosh(x^2/2 + x^4/4) )); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Jul 02 2019
    
  • Mathematica
    With[{n=30}, CoefficientList[Series[Exp[x]*Cosh[x^2/2 + x^4/4], {x, 0, n}], x]*Range[0, n]!] (* G. C. Greubel, Jul 02 2019 *)
  • PARI
    my(x='x+O('x^30)); Vec(serlaplace( exp(x)*cosh(x^2/2 + x^4/4) )) \\ G. C. Greubel, Jul 02 2019
    
  • Sage
    m = 30; T = taylor(exp(x)*cosh(x^2/2 + x^4/4), x, 0, m); [factorial(n)*T.coefficient(x, n) for n in (0..m)] # G. C. Greubel, Jul 02 2019

Formula

E.g.f.: exp(x)*cosh(x^2/2 + x^4/4).

A190865 E.g.f. exp(x+x^3/6).

Original entry on oeis.org

1, 1, 1, 2, 5, 11, 31, 106, 337, 1205, 5021, 20186, 86461, 417847, 1992355, 9860306, 53734241, 292816841, 1633818457, 9855157330, 59926837141, 370352343971, 2439935383271, 16283034762842, 109982177787505, 783404343570301, 5668314772422901, 41412522553362026
Offset: 0

Views

Author

Vladimir Kruchinin, May 22 2011

Keywords

Comments

a(n) is the number of set partitions of {1,2,...,n} such that the size of each block divides 3. - Geoffrey Critzer, Sep 23 2011

Examples

			a(0) = 1 because (vacuously) all sizes of the blocks in the unique set partition of {} divide 3.
a(4) = 5 because there are 5 such set partitions of {1,2,3,4}: ({1},{2,3,4}) ({2},{1,3,4}) ({3},{1,2,4}) ({4},{1,2,3}) ({1},{2},{3},{4}).
		

Crossrefs

Cf. A001470.
Column k=3 of A275422.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, add(
          `if`(j>n, 0, a(n-j)*binomial(n-1, j-1)), j=[1, 3]))
        end:
    seq(a(n), n=0..30);  # Alois P. Heinz, Jul 27 2016
  • Mathematica
    Range[0, 25]! CoefficientList[Series[Exp[x + x^3/6] , {x, 0, 25}], x]
  • Maxima
    a(n):=n!*sum(1/((k)!*(n-3*k)!*6^(k)),k,0,n/3);

Formula

a(n) = n!*sum(k=0..n/3, 1/((k)!*(n-3*k)!*6^(k))), n>0, a(0)=1.
E.g.f.: E(0)/2, where E(k)= 1 + 1/(1 - x*(6+x^2)/(x*(6+x^2)+ 6*(k+1)/E(k+1))); (continued fraction). - Sergei N. Gladkovskii, Jun 01 2013
Recurrence: 2*a(n) = 2*a(n-1) + (n-2)*(n-1)*a(n-3). - Vaclav Kotesovec, Jun 27 2013
a(n) ~ n^(2*n/3) * exp(-2*n/3+(2*n)^(1/3)) / (sqrt(3)*2^(n/3)) * (1 - 2^(2/3)/(6*n^(1/3)) + 13*2^(1/3)/(36*n^(2/3))). - Vaclav Kotesovec, Jun 27 2013
a(n) = hypergeom([-n/3, (1 - n)/3, (2 - n)/3], [], -9/2). - Peter Luschny, Jun 04 2021

A053497 Number of degree-n permutations of order dividing 7.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 721, 5761, 25921, 86401, 237601, 570241, 1235521, 892045441, 13348249201, 106757164801, 604924594561, 2722120577281, 10344007402561, 34479959558401, 24928970490633601, 546446134633639681, 6281586217487489041, 50248618811434961281
Offset: 0

Views

Author

N. J. A. Sloane, Jan 15 2000

Keywords

References

  • R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Example 5.2.10.

Crossrefs

Sequences with e.g.f. exp(x + x^m/m): A000079 (m=1), A000085 (m=2), A001470 (m=3), A118934 (m=4), A052501 (m=5), A293588 (m=6), this sequence (m=7).
Column k=7 of A008307.

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 31); Coefficients(R!(Laplace( Exp(x + x^7/7) ))); // G. C. Greubel, May 14 2019, Mar 07 2021
    
  • Maple
    a:= proc(n) option remember; `if`(n<0, 0, `if`(n=0, 1,
           add(mul(n-i, i=1..j-1)*a(n-j), j=[1, 7])))
        end:
    seq(a(n), n=0..25); # Alois P. Heinz, Feb 14 2013
  • Mathematica
    CoefficientList[Series[Exp[x+x^7/7], {x, 0, 24}], x]*Range[0, 24]! (* Jean-François Alcover, Mar 24 2014 *)
  • PARI
    my(x='x+O('x^30)); Vec(serlaplace( exp(x+x^7/7) )) \\ G. C. Greubel, May 14 2019
    
  • Sage
    f=factorial; [sum(f(n)/(7^j*f(j)*f(n-7*j)) for j in (0..n/7)) for n in (0..30)] # G. C. Greubel, May 14 2019

Formula

E.g.f.: exp(x + x^7/7).
a(n) = Sum_{k=0..floor(n/7)} n!/(7^k*k!*(n-7*k)!). - G. C. Greubel, Mar 07 2021

A061136 Number of degree-n odd permutations of order dividing 4.

Original entry on oeis.org

0, 0, 1, 3, 12, 40, 120, 336, 2128, 13392, 118800, 850960, 6004416, 38408448, 260321152, 1744135680, 17067141120, 167200393216, 1838196972288, 18345298804992, 181218866222080, 1673804042803200, 16992835499329536
Offset: 0

Views

Author

Vladeta Jovovic, Apr 14 2001

Keywords

Crossrefs

Formula

E.g.f.: 1/2*exp(x + 1/2*x^2 + 1/4*x^4) - 1/2*exp(x - 1/2*x^2 - 1/4*x^4).

A362043 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = n! * Sum_{j=0..floor(n/3)} (k/6)^j * binomial(n-2*j,j)/(n-2*j)!.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3, 5, 1, 1, 1, 1, 4, 9, 11, 1, 1, 1, 1, 5, 13, 21, 31, 1, 1, 1, 1, 6, 17, 31, 81, 106, 1, 1, 1, 1, 7, 21, 41, 151, 351, 337, 1, 1, 1, 1, 8, 25, 51, 241, 736, 1233, 1205, 1, 1, 1, 1, 9, 29, 61, 351, 1261, 2689, 5769, 5021, 1
Offset: 0

Views

Author

Seiichi Manyama, Apr 15 2023

Keywords

Examples

			Square array begins:
  1,  1,  1,   1,   1,   1,   1, ...
  1,  1,  1,   1,   1,   1,   1, ...
  1,  1,  1,   1,   1,   1,   1, ...
  1,  2,  3,   4,   5,   6,   7, ...
  1,  5,  9,  13,  17,  21,  25, ...
  1, 11, 21,  31,  41,  51,  61, ...
  1, 31, 81, 151, 241, 351, 481, ...
		

Crossrefs

Columns k=0..2 give A000012, A190865, A001470.
Main diagonal gives A362173.
T(n,2*n) gives A362300.
T(n,6*n) gives A362301.

Programs

  • PARI
    T(n, k) = n!*sum(j=0, n\3, (k/6)^j/(j!*(n-3*j)!));

Formula

E.g.f. of column k: exp(x + k*x^3/6).
T(n,k) = T(n-1,k) + k * binomial(n-1,2) * T(n-3,k) for n > 2.
T(n,k) = n! * Sum_{j=0..floor(n/3)} (k/6)^j / (j! * (n-3*j)!).
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