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 1-9 of 9 results.

A134375 a(n) = (n!)^4.

Original entry on oeis.org

1, 1, 16, 1296, 331776, 207360000, 268738560000, 645241282560000, 2642908293365760000, 17340121312772751360000, 173401213127727513600000000, 2538767161403058526617600000000, 52643875858853821607942553600000000, 1503561738404723998944447273369600000000
Offset: 0

Views

Author

Artur Jasinski, Oct 22 2007

Keywords

Comments

a(n) is also the determinant of the symmetric n X n matrix M defined by M(i,j) = sigma_4(gcd(i,j)) for 1 <= i,j <= n, and n>0, where sigma_4 is A001159. - Enrique Pérez Herrero, Aug 13 2011

Crossrefs

Programs

  • Maple
    a:= n-> (n!)^4:
    seq(a(n), n=0..20);  # Alois P. Heinz, Aug 15 2013
  • Mathematica
    Table[((n)!)^(4), {n, 0, 10}]

Formula

a(n) = det(S(i+4,j), 1 <= i,j <= n), where S(n,k) are Stirling numbers of the second kind. - Mircea Merca, Apr 04 2013

A134374 a(n) = ((2n+1)!)^2.

Original entry on oeis.org

1, 36, 14400, 25401600, 131681894400, 1593350922240000, 38775788043632640000, 1710012252724199424000000, 126513546505547170185216000000, 14797530453474819213543604224000000
Offset: 0

Views

Author

Artur Jasinski, Oct 22 2007

Keywords

Crossrefs

Programs

Formula

a(n) = A009445(n)^2 = A001044(2n+1). - Wesley Ivan Hurt, May 02 2014
From Amiram Eldar, Nov 16 2020: (Start)
Sum_{n>=0} 1/a(n) = A334378.
Sum_{n>=0} (-1)^n/a(n) = Im(BesselJ(0, 2*exp(3*Pi*i/4))). (End)

A134369 a(n) = ((2n+1)!)^(n+1).

Original entry on oeis.org

1, 36, 1728000, 645241282560000, 6292383221978976013516800000, 4045146997974190235742848547815424000000000000, 363046466970952735968096996065196818096105852014637875200000000000000
Offset: 0

Views

Author

Artur Jasinski, Oct 22 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((2n+1)!)^(n + 1), {n, 0, 10}]

Formula

a(n) ~ 2^(2*(n+1)^2) * exp(13/24 - 2*n*(n+1)) * n^((n+1)*(4*n+3)/2) * Pi^((n+1)/2). - Vaclav Kotesovec, Oct 26 2017

A134371 a(n) = ((2n)!)^n.

Original entry on oeis.org

1, 2, 576, 373248000, 2642908293365760000, 629238322197897601351680000000000, 12078744213598964456884373878200091017216000000000000
Offset: 0

Views

Author

Artur Jasinski, Oct 22 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((2n)!)^(n), {n, 0, 10}]

Formula

a(n) ~ 2^(n*(2*n+1)) * exp(1/24 - 2*n^2) * n^(n*(4*n+1)/2) * Pi^(n/2). - Vaclav Kotesovec, Oct 26 2017

A134372 a(n) = ((2n)!)^2.

Original entry on oeis.org

1, 4, 576, 518400, 1625702400, 13168189440000, 229442532802560000, 7600054456551997440000, 437763136697395052544000000, 40990389067797283140009984000000, 5919012181389927685417441689600000000
Offset: 0

Views

Author

Artur Jasinski, Oct 22 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((2n)!)^(2), {n, 0, 10}]
    ((2*Range[0,20])!)^2 (* Harvey P. Dale, Jul 14 2011 *)
  • PARI
    a(n) = ((2*n)!)^2; \\ Michel Marcus, Nov 16 2020

Formula

From Amiram Eldar, Nov 16 2020: (Start)
Sum_{n>=0} 1/a(n) = A334379.
Sum_{n>=0} (-1)^n/a(n) = A334632. (End)

A134370 a(n) = ((2n+1)!)^(n+2).

Original entry on oeis.org

1, 216, 207360000, 3252016064102400000, 2283380023591730815784976384000000, 161469323688736156802100136913438716723200000000000000, 2260697901194635682690248130915498742378267539496871953338204160000000000000000
Offset: 0

Views

Author

Artur Jasinski, Oct 22 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((2n+1)!)^(n + 2), {n, 0, 10}]

Formula

a(n) ~ 2^(2*(n+1)*(n+2)) * exp(13/24 - 2*n*(n+2)) * n^((n+2)*(4*n+3)/2) * Pi^(n/2 + 1). - Vaclav Kotesovec, Oct 26 2017

Extensions

Typo in a(6) corrected by Georg Fischer, Apr 10 2024

A134373 a(n) = ((2n)!)^3.

Original entry on oeis.org

1, 8, 13824, 373248000, 65548320768000, 47784725839872000000, 109903340320478724096000000, 662559760549147780765974528000000, 9159226129831418921308831875072000000000, 262435789155225791087396177124997988352000000000
Offset: 0

Views

Author

Artur Jasinski, Oct 22 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((2n)!)^(3), {n, 0, 10}]
    ((2*Range[0, 10])!)^3 (* Harvey P. Dale, Jul 25 2016 *)
  • Sage
    [factorial(2*n)**3 for n in range(0,9)] # Stefano Spezia, Apr 22 2025

Extensions

Definition corrected by Harvey P. Dale, Jul 25 2016

A351580 a(n) is the number of multisets of size n-1 consisting of permutations of n elements.

Original entry on oeis.org

1, 2, 21, 2600, 9078630, 1634935320144, 22831938997720867560, 34390564970975286088924022400, 7457911916650283082000186530740981347120, 300682790088737748950725540713718365319268411170195200, 2830053444386286847574443631356044745870287426798365860653876609636480
Offset: 1

Views

Author

Dan Eilers, Feb 13 2022

Keywords

Comments

a(n) is the number of reduced men's ranking tables in the stable marriage problem of order n. In the SMP (as noted in A351409), relabeling men or women has no effect on the number of stable matchings. So the women can be relabeled to normalize the order of man #1's rankings (with woman #1 as his first choice and woman n as his last choice), and then the men except man #1 can be relabeled to normalize the lexicographic order of those men's rankings. Since man #1's rankings end up fixed in natural order, they do not contribute to the number of possibilities, leaving n! multichoose (n-1) ways to arrange the rankings of the other n-1 men.
The number of unreduced men's ranking tables is given by A036740. Relabeling just the women reduces this to A134366. Alternately, relabeling just the men reduces A036740 to A344690. Relabeling both men and women reduces the men's relabeling reduction, A344690, by a factor of (n!+n-1)/n to a(n).
It might be tempting to try to reduce A344690 by a factor of n!, but that doesn't work because not all of man #1's rankings are equally likely after relabeling all the men to give man #1 the lexicographically least rankings.
There is room for further relabeling reduction from a(n), given by A263921. The reduction from a(n) to A263921 is analogous to the reduction from reduced latin squares, A000315, to A123234.
Each of the a(n) reduced men's ranking tables can be combined with the A036740 possible unreduced women's ranking tables to form complete instances, but these instances have more possibilities than A351409. For example, a(3)*A036740(3)=21*216=4536 > A351409(3)=3888. However, fewer possibilities result from using A263921 in place of a(n), although the men's ranking tables of A263921 may not be as straightforward to generate. With A263921(3)=10, 10*216=2160 < 3888.

Examples

			Starting with the following men's ranking table of order 3, where row k represents man k's rankings, the 1 in the 2nd position of row 3 means that man #3 ranks woman #2 as his 1st choice.
  213
  321
  213
Step 1: reorder columns so row 1 is in natural order:
  123
  231
  123
Step 2: reorder rows 2 to n so rows are in lexical order:
  123
  123
  231
a(3)=21 because there are 1+2+3+4+5+6 = 21 possibilities for the last two rows in lexical order, with 3!=6 possible permutations for each row.
The 21 tables for a(3) are the following:
  123   123   123   123   123   123   123
  123   123   123   123   123   123   132
  123   132   213   231   312   321   132
.
  123   123   123   123   123   123   123
  132   132   132   132   213   213   213
  213   231   312   321   213   231   312
.
  123   123   123   123   123   123   123
  213   231   231   231   312   312   321
  321   231   312   321   312   321   321
		

Crossrefs

Programs

  • Mathematica
    Table[Binomial[n!+n-2,n-1],{n,15}] (* Harvey P. Dale, Jun 02 2023 *)
  • PARI
    a(n) = binomial(n! + n - 2, n - 1) \\ Andrew Howroyd, Feb 13 2022

Formula

a(n) = binomial(n! + n - 2, n - 1).
a(n) = n*A344690(n)/A030495(n-1).
a(n) = A344690*n/(n! + n - 1).
a(n) = A071919(n-1,n!). - Alois P. Heinz, Feb 16 2022

Extensions

Erroneous Mathematica program deleted by N. J. A. Sloane, Jun 02 2023

A127488 a(n) = (n^2)!/(2*(n!)).

Original entry on oeis.org

6, 30240, 435891456000, 64630041847212441600000, 258328699159653623241666283438080000000
Offset: 2

Views

Author

Artur Jasinski, Jan 16 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Table[(n^2)!/(2(n!)), {n, 2, 6}]

Formula

a(n) ~ n^(2*n^2 - n + 1/2) / (2 * exp(n*(n-1))). - Vaclav Kotesovec, Oct 26 2017
Showing 1-9 of 9 results.