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 1-6 of 6 results.

A022915 Multinomial coefficients (0, 1, ..., n)! = C(n+1,2)!/(0!*1!*2!*...*n!).

Original entry on oeis.org

1, 1, 3, 60, 12600, 37837800, 2053230379200, 2431106898187968000, 73566121315513295589120000, 65191584694745586153436251091200000, 1906765806522767212441719098019963758016000000, 2048024348726152339387799085049745725891853852479488000000
Offset: 0

Views

Author

Keywords

Comments

Number of ways to put numbers 1, 2, ..., n*(n+1)/2 in a triangular array of n rows in such a way that each row is increasing. Also number of ways to choose groups of 1, 2, 3, ..., n-1 and n objects out of n*(n+1)/2 objects. - Floor van Lamoen, Jul 16 2001
a(n) is the number of ways to linearly order the multiset {1,2,2,3,3,3,...n,n,...n}. - Geoffrey Critzer, Mar 08 2009
Also the number of distinct adjacency matrices in the n-triangular honeycomb rook graph. - Eric W. Weisstein, Jul 14 2017

Examples

			From _Gus Wiseman_, Aug 12 2020: (Start)
The a(3) = 60 permutations of the prime indices of A006939(3) = 360:
  (111223)  (121123)  (131122)  (212113)  (231211)
  (111232)  (121132)  (131212)  (212131)  (232111)
  (111322)  (121213)  (131221)  (212311)  (311122)
  (112123)  (121231)  (132112)  (213112)  (311212)
  (112132)  (121312)  (132121)  (213121)  (311221)
  (112213)  (121321)  (132211)  (213211)  (312112)
  (112231)  (122113)  (211123)  (221113)  (312121)
  (112312)  (122131)  (211132)  (221131)  (312211)
  (112321)  (122311)  (211213)  (221311)  (321112)
  (113122)  (123112)  (211231)  (223111)  (321121)
  (113212)  (123121)  (211312)  (231112)  (321211)
  (113221)  (123211)  (211321)  (231121)  (322111)
(End)
		

Crossrefs

A190945 counts the case of anti-run permutations.
A317829 counts partitions of this multiset.
A325617 is the version for factorials instead of superprimorials.
A006939 lists superprimorials or Chernoff numbers.
A008480 counts permutations of prime indices.
A181818 gives products of superprimorials, with complement A336426.

Programs

  • Maple
    with(combinat):
    a:= n-> multinomial(binomial(n+1, 2), $0..n):
    seq(a(n), n=0..12);  # Alois P. Heinz, May 18 2013
  • Mathematica
    Table[Apply[Multinomial ,Range[n]], {n, 0, 20}]  (* Geoffrey Critzer, Dec 09 2012 *)
    Table[Multinomial @@ Range[n], {n, 0, 20}] (* Eric W. Weisstein, Jul 14 2017 *)
    Table[Binomial[n + 1, 2]!/BarnesG[n + 2], {n, 0, 20}] (* Eric W. Weisstein, Jul 14 2017 *)
    Table[Length[Permutations[Join@@Table[i,{i,n},{i}]]],{n,0,4}] (* Gus Wiseman, Aug 12 2020 *)
  • PARI
    a(n) = binomial(n+1,2)!/prod(k=1, n, k^(n+1-k)); \\ Michel Marcus, May 02 2019

Formula

a(n) = (n*(n+1)/2)!/(0!*1!*2!*...*n!).
a(n) = a(n-1) * A014068(n). - Dan Fux (dan.fux(AT)OpenGaia.com or danfux(AT)OpenGaia.com), Apr 08 2001.
a(n) = A052295(n)/A000178(n). - Lekraj Beedassy, Feb 19 2004
a(n) = A208437(n*(n+1)/2,n). - Alois P. Heinz, Apr 08 2016
a(n) ~ A * exp(n^2/4 + n + 1/6) * n^(n^2/2 + 7/12) / (2^((n+1)^2/2) * Pi^(n/2)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, May 02 2019
a(n) = A327803(n*(n+1)/2,n). - Alois P. Heinz, Sep 25 2019
a(n) = A008480(A006939(n)). - Gus Wiseman, Aug 12 2020

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Apr 11 2001
More terms from Michel ten Voorde, Apr 12 2001
Better definition from L. Edson Jeffery, May 18 2013

A060371 a(n) = (prime(n) - 1)! + 1.

Original entry on oeis.org

2, 3, 25, 721, 3628801, 479001601, 20922789888001, 6402373705728001, 1124000727777607680001, 304888344611713860501504000001, 265252859812191058636308480000001, 371993326789901217467999448150835200000001
Offset: 1

Views

Author

Jason Earls, Apr 01 2001

Keywords

Comments

If the prime p is in A055469, that is if p = 2, 7, 11, 29, ... = A055469(j) which is valid for the first, 4th, 5th, 10th,.... entry here with j = 1, 2, 3, ..., then a(n) = A052295[A067186(j)] + 1. - R. J. Mathar, Apr 27 2007
It follows from Wilson's theorem that a(n) is divisible by the n-th prime. - Alonso del Arte, Feb 07 2014

Crossrefs

Subsequence of A038507. - Michel Marcus, Oct 17 2017

Programs

  • Magma
    [Factorial(NthPrime(n)-1)+1: n in [1..15]]; // Vincenzo Librandi, Oct 17 2017
  • Mathematica
    Table[(Prime[n] - 1)! + 1, {n, 12}] (* Alonso del Arte, Feb 07 2014 *)
  • PARI
    { n=1; forprime (p=1, 524, write("b060371.txt", n++, " ", (p - 1)! + 1); ) } \\ Harry J. Smith, Jul 04 2009
    

Extensions

Corrected offset by Alonso del Arte, Feb 07 2014

A283261 Product of the different products of subsets of the set of numbers from 1 to n.

Original entry on oeis.org

1, 1, 2, 36, 331776, 42998169600000000, 13974055172471046820331520000000000000, 1833132881579690383668380351534446872452674453158326975200092938148249600000000000000000000000000
Offset: 0

Views

Author

Jaroslav Krizek, Mar 04 2017

Keywords

Comments

Product of numbers in n-th row of A070861.

Examples

			Rows with subsets of the sets of numbers from 1 to n:
  {},
  {}, {1};
  {}, {1}, {2}, {1, 2};
  {}, {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3};
  ...
Rows with the products of elements of these subsets:
  1;
  1, 1;
  1, 1, 2, 2;
  1, 1, 2, 3, 2, 3, 6, 6;
  ...
Rows with the different products of elements of these subsets:
  1;
  1;
  1, 2;
  1, 2, 3, 6;
  ...
a(0) = 1, a(1) = (1), a(2) = (1*2) = 2, a(3) = (1*2*3*6) = 36, ... .
		

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, {1},
          map(x-> [x, x*n][], b(n-1)))
        end:
    a:= n-> mul(i, i=b(n)):
    seq(a(n), n=0..7);  # Alois P. Heinz, Aug 01 2022
  • Mathematica
    Table[Times @@ Union@ Map[Times @@ # &, Subsets@ Range@ n], {n, 7}] (* Michael De Vlieger, Mar 05 2017 *)
  • PARI
    a(n)=my(v=[2..n]); factorback(Set(vector(2^(n-1),i, factorback(vecextract(v,i-1))))) \\ Charles R Greathouse IV, Mar 06 2017

Formula

a(n) <= n!^((A000005(n!))/2) = n!^(A027423(n)/2). - David A. Corneth, Mar 05 2017
a(n) = n!^(A263292(n)). - David A. Corneth, Mar 06 2017

Extensions

a(0)=1 prepended by Alois P. Heinz, Aug 01 2022

A351884 Irregular triangle read by rows: T(n,k) is the number of sets of lists with distinct block sizes (as in A088311(n)) and containing exactly k lists.

Original entry on oeis.org

1, 0, 1, 0, 2, 0, 6, 6, 0, 24, 24, 0, 120, 240, 0, 720, 1440, 720, 0, 5040, 15120, 5040, 0, 40320, 120960, 80640, 0, 362880, 1451520, 1088640, 0, 3628800, 14515200, 14515200, 3628800, 0, 39916800, 199584000, 199584000, 39916800, 0, 479001600, 2395008000, 3353011200, 958003200
Offset: 0

Views

Author

Geoffrey Critzer, Feb 23 2022

Keywords

Examples

			Triangle T(n,k) begins:
  1;
  0,     1;
  0,     2;
  0,     6,      6;
  0,    24,     24;
  0,   120,    240;
  0,   720,   1440,   720;
  0,  5040,  15120,  5040;
  0, 40320, 120960, 80640;
  ...
		

Crossrefs

Columns k=0-1 give: A000007, A000142 (for n>=1).
Cf. A088311 (row sums).
T(A000217(n),n) gives A052295.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1)+expand(x*b(n-i, min(i-1, n-i)))*n!/(n-i)!))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=0..degree(p)))(b(n$2)):
    seq(T(n), n=0..12);  # Alois P. Heinz, Feb 23 2022
  • Mathematica
    nn = 13; Prepend[Map[Prepend[#, 0] &, Drop[Map[Select[#, # > 0 &] &,Range[0, nn]! CoefficientList[Series[Product[1 + y x^i, {i, 1, nn}], {x, 0, nn}],{x,y}]], 1]], {1}] // Grid

Formula

E.g.f.: Product_{i>=1} (1 + y*x^i).
Sum_{k=0..A003056(n)} (-1)^k * T(n,k) = A293140(n). - Alois P. Heinz, Feb 23 2022

A091478 Table of graphs with n (>=0) nodes and k (>=0) edges. Each type of object labeled from its own label set.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 6, 6, 1, 6, 30, 120, 360, 720, 720, 1, 10, 90, 720, 5040, 30240, 151200, 604800, 1814400, 3628800, 3628800, 1, 15, 210, 2730, 32760, 360360, 3603600, 32432400, 259459200, 1816214400, 10897286400, 54486432000, 217945728000, 653837184000, 1307674368000, 1307674368000
Offset: 0

Views

Author

Christian G. Bower, Jan 13 2004

Keywords

Examples

			  1;
  1;
  1, 1;
  1, 3,  6,   6;
  1, 6, 30, 120, 360, 720, 720;
  ...
		

References

  • F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, p. 114 (2.4.44).

Crossrefs

Row sums: A091479.
Row lengths: A000124(n-1) for n>=1.
Columns 0-2: A000012, A000217(n-1), A033487(n-2).
a(n,A000217(n-1)) = A052295(n-1).

Formula

a(n, k) = k!*binomial(binomial(n, 2), k).

Extensions

T(0,0)=1 prepended by Alois P. Heinz, Feb 14 2023

A374293 a(n)/binomial(n,2)! is the probability that the minimum spanning tree of the complete graph of n vertices with i.i.d. random edge weights is a specific path.

Original entry on oeis.org

1, 1, 2, 44, 27120, 882241920, 2443792425984000, 846533597741050576896000, 50571850611494440562578575851520000, 686805008584962439650318114385825747697664000000, 2701735270674169239689693528384644314472371275610193920000000000, 3819958423456547324072333722421751679308286064300212197312630212725309440000000000
Offset: 1

Views

Author

Jamie Tucker-Foltz, Jul 02 2024

Keywords

Comments

Equivalently, a(n) is the number of orderings of the edges of the complete graph of n vertices such that the minimal spanning tree (e.g., obtained by running Kruskal's algorithm with the edges in that order) is a specific path.
It appears that this is a subsequence of A253950. Specifically, a(n) appears at index m - n + 3, where m = binomial(n,2) is the number of edges of the complete graph on n vertices.

Examples

			a(3) = 2 because there are 2 orderings of the edges a, b, and c of K_3 that give the path {a, b}: (a, b, c) and (b, a, c).
		

Crossrefs

Programs

  • PARI
    E(p,m)={sum(k=0, m, sum(i=0, k, polcoef(p, i)*i!*(m-i)! )*x^k/(k!*(m-k)!))}
    seq(n)={my(v=vector(n)); v[1]=1; for(n=2, n, my(p=sum(k=1, n-1, v[k]*v[n-k])); v[n]=E(intformal(p), binomial(n,2))); vector(n, n, my(m=binomial(n,2)); m!*polcoef(v[n], m))} \\ Andrew Howroyd, Jul 31 2024
Showing 1-6 of 6 results.