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 1-7 of 7 results.

A102456 a(n) = n!/A102356(n).

Original entry on oeis.org

1, 1, 2, 2, 4, 8, 12, 24, 48, 96, 288, 576, 1152, 2304, 6912, 13824, 27648, 82944, 165888, 497664, 1327104, 2985984, 7962624, 19906560, 59719680, 143327232, 358318080, 955514880, 2866544640, 7644119040, 17199267840, 51597803520, 137594142720, 412782428160
Offset: 0

Views

Author

Vladeta Jovovic, Feb 23 2005

Keywords

Programs

  • Maple
    b:= proc(n, i) option remember;
          `if`(n=0, 1, `if` (i<1, 0,
           max(seq(b(n-i*j, i-1) *n!/i!^j/(n-i*j)!/j!, j=0..n/i))))
        end:
    a:= n-> n!/b(n, n):
    seq(a(n), n=0..50);  # Alois P. Heinz, Jun 01 2012
  • Mathematica
    b[0, ] = 1; b[, ?NonPositive] = 0; b[n, i_] := b[n, i] = Max[Table[b[n - i*j, i - 1]*n!/i!^j/(n - i*j)!/j!, {j, 0, n/i}]]; a[n_] := n!/b[n, n]; Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Jan 24 2014, after Alois P. Heinz *)

A130760 Noncrossing set partition version of A102356.

Original entry on oeis.org

1, 1, 1, 3, 6, 10, 30, 105, 280, 756, 2520, 6930, 18480, 60060, 180180, 675675, 2162160, 6806800, 24504480, 77597520, 232792560, 888844320, 3259095840, 10708457760, 37479602160, 133855722000, 435031096500, 1445641797600, 5059746291600, 17468171721000, 58227239070000
Offset: 0

Views

Author

Dan Drake, Jul 13 2007

Keywords

Examples

			a(7) = 105 because there are 105 noncrossing set partitions of {1,2,3,4,5,6,7} of type {3,2,1,1} and all other integer partitions of 7 produce fewer noncrossing set partitions.
		

References

  • D. E. Knuth, The Art of Computer Programming, vol. 4, section 7.2.1.5, problem 65.

Crossrefs

Cf. A102356.

Programs

  • Mathematica
    <Vaclav Kotesovec, Oct 23 2014 *)

Extensions

More terms from Vaclav Kotesovec, Oct 23 2014

A080575 Triangle of multinomial coefficients, read by rows (version 2).

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 4, 3, 6, 1, 1, 5, 10, 10, 15, 10, 1, 1, 6, 15, 15, 10, 60, 20, 15, 45, 15, 1, 1, 7, 21, 21, 35, 105, 35, 70, 105, 210, 35, 105, 105, 21, 1, 1, 8, 28, 28, 56, 168, 56, 35, 280, 210, 420, 70, 280, 280, 840, 560, 56, 105, 420, 210, 28, 1, 1, 9, 36, 36, 84, 252, 84, 126, 504, 378, 756, 126, 315, 1260, 1260, 1890, 1260, 126, 280, 2520, 840, 1260, 3780, 1260, 84, 945, 1260, 378, 36, 1, 1, 10, 45, 45, 120, 360, 120, 210, 840, 630, 1260, 210
Offset: 1

Views

Author

Wouter Meeussen, Mar 23 2003

Keywords

Comments

This is different from A036040 and A178867.
T[n,m] = count of set partitions of n with block lengths given by the m-th partition of n in the canonical ordering.
From Tilman Neumann, Oct 05 2008: (Start)
These are also the coefficients occurring in complete Bell polynomials, Faa di Bruno's formula (in its simplest form) and computation of moments from cumulants.
Though the Bell polynomials seem quite unwieldy, they can be computed easily as the determinant of an n-dimensional square matrix. (see e.g. [Coffey] and program below)
The complete Bell polynomial of the first n primes gives A007446. (End)
The difference with A036040 and A178867 lies in the ordering of the monomials. This sequence uses lexicographic ordering, while in A036040 the total order (power) of the monomials prevails (Abramowitz-Stegun style): e.g., in row 6 we have ...+ 15*x[3]*x[5] + 15*x[3]*x[6]^2 + 10*x[4]^2 +...; in A036040 the coefficient of x[3]*x[6]^2 would come after that of x[4]^2 because the total order is higher, here it comes before in view of the lexicographic order. - M. F. Hasler, Jul 12 2015

Examples

			For n=4 the 5 integer partitions in canonical ordering with corresponding set partitions and counts are:
   [4]       -> #{1234} = 1
   [3,1]     -> #{123/4, 124/3, 134/2, 1/234} = 4
   [2,2]     -> #{12/34, 13/24, 14/23} = 3
   [2,1,1]   -> #{12/3/4, 13/2/4, 1/23/4, 14/2/3, 1/24/3, 1/2/34} = 6
   [1,1,1,1] -> #{1/2/3/4} = 1
Thus row 4 is [1, 4, 3, 6, 1].
Triangle begins:
1;
1, 1;
1, 3,  1;
1, 4,  3,  6,  1;
1, 5, 10, 10, 15,  10,  1;
1, 6, 15, 15, 10,  60, 20, 15,  45,  15,  1;
1, 7, 21, 21, 35, 105, 35, 70, 105, 210, 35, 105, 105, 21, 1;
...
Row 4 represents 1*k(4)+4*k(3)*k(1)+3*k(2)^2+6*k(2)*k(1)^2+1*k(1)^4 and T(4,4)=6 since there are six ways of partitioning four labeled items into one part with two items and two parts each with one item.
		

References

  • See A036040 for the column labeled "M_3" in Abramowitz and Stegun, Handbook, p. 831.

Crossrefs

See A036040 for another version. Cf. A036036-A036039.
Row sums are A000110.
Row lengths are A000041.
Cf. A007446. - Tilman Neumann, Oct 05 2008
Cf. A178866 and A178867 (version 3). - Johannes W. Meijer, Jun 21 2010
Maximum value in row n gives A102356(n).

Programs

  • Mathematica
    runs[li:{__Integer}] := ((Length/@ Split[ # ]))&[Sort@ li]; Table[Apply[Multinomial, IntegerPartitions[w], {1}]/Apply[Times, (runs/@ IntegerPartitions[w])!, {1}], {w, 6}]
    (* Second program: *)
    completeBellMatrix[x_, n_] := Module[{M, i, j}, M[, ] = 0; For[i=1, i <= n-1 , i++, M[i, i+1] = -1]; For[i=1, i <= n , i++, For[j=1, j <= i, j++, M[i, j] = Binomial[i-1, j-1]*x[i-j+1]]]; Array[M, {n, n}]]; completeBellPoly[x_, n_] := Det[completeBellMatrix[x, n]]; row[n_] := List @@ completeBellPoly[x, n] /. x[] -> 1 // Reverse; Table[row[n], {n, 1, 10}] // Flatten (* _Jean-François Alcover, Aug 31 2016, after Tilman Neumann *)
    B[0] = 1;
    B[n_] := B[n] = Sum[Binomial[n-1, k] B[n-k-1] x[k+1], {k, 0, n-1}]//Expand;
    row[n_] := Reverse[List @@ B[n] /. x[_] -> 1];
    Table[row[n], {n, 1, 10}] // Flatten (* Jean-François Alcover, Aug 10 2018, after Wolfdieter Lang *)
  • MuPAD
    completeBellMatrix := proc(x,n) // x - vector x[1]...x[m], m>=n
    local i,j,M; begin M:=matrix(n,n): // zero-initialized
    for i from 1 to n-1 do M[i,i+1]:=-1: end_for:
    for i from 1 to n do for j from 1 to i do
        M[i,j] := binomial(i-1,j-1)*x[i-j+1]:
    end_for: end_for:
    return (M): end_proc:
    completeBellPoly := proc(x, n) begin
    return (linalg::det(completeBellMatrix(x,n))): end_proc:
    for i from 1 to 10 do print(i,completeBellPoly(x,i)): end_for:
    // Tilman Neumann, Oct 05 2008
    
  • PARI
    \\ See links.
    
  • PARI
    A080575_poly(n,V=vector(n,i,eval(Str('x,i))))={matdet(matrix(n,n,i,j,if(j<=i,binomial(i-1,j-1)*V[n-i+j],-(j==i+1))))}
    A080575_row(n)={(f(s)=if(type(s)!="t_INT",concat(apply(f,select(t->t,Vec(s)))),s))(A080575_poly(n))} \\ M. F. Hasler, Jul 12 2015

A102462 Max{ k!/(a(1)!*a(2)!*..*a(n)!) : a(1) + 2*a(2) + 3*a(3) + ... + n*a(n) = n, a(1) + a(2) + ... + a(n) = k }.

Original entry on oeis.org

1, 1, 1, 2, 3, 4, 6, 12, 20, 30, 60, 105, 168, 280, 504, 840, 1512, 2520, 5040, 9240, 15840, 27720, 55440, 102960, 180180, 360360, 675675, 1201200, 2162160, 4084080, 7351344, 12697776, 24504480, 46558512, 84651840, 155195040, 296281440, 543182640, 961015440
Offset: 0

Views

Author

Vladeta Jovovic, Feb 23 2005

Keywords

Comments

a(n) is the greatest number in row n of A048996 and in row n of A072811. Thus a(n) is the greatest number of compositions (permutations) obtainable from some partition of n. Example: a(7)=12 is the greatest number of compositions from some partition of 7, specifically, the partition {3,2,1,1}. - Clark Kimberling, Dec 24 2006
The partition(s) giving this optimum is always one where #{parts equal to i} >= #{parts equal to j} if i <= j. These partitions are counted in A007294. - Franklin T. Adams-Watters, Apr 08 2008
The number of partition(s) giving this optimum is given by A198254. - Olivier Gérard, Nov 17 2011

Crossrefs

Programs

  • Maple
    b:= proc(n,i,p) option remember; `if`(n=0 or i=1, (p+n)!/n!,
           max(seq(b(n-i*j, i-1, p+j)/j!, j=0..n/i)))
        end:
    a:= n-> b(n$2, 0):
    seq(a(n), n=0..50);  # Alois P. Heinz, Apr 15 2015
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[n == 0 || i == 1, (p + n)!/n!, Max[Table[ b[n-i*j, i-1, p+j]/j!, {j, 0, n/i}]]]; a[n_] := b[n, n, 0]; Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Dec 19 2015, after Alois P. Heinz *)

A211350 Refined triangle A124323: T(n,k) is the number of partitions of an n-set that are of type k (k-th integer partition, defined by A194602).

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 6, 4, 3, 1, 1, 10, 10, 15, 5, 10, 1, 1, 15, 20, 45, 15, 60, 6, 15, 15, 10, 1, 1, 21, 35, 105, 35, 210, 21, 105, 105, 70, 7, 105, 21, 35, 1, 1, 28, 56, 210, 70, 560, 56, 420, 420, 280, 28, 840, 168, 280, 8, 105, 210, 280, 28
Offset: 1

Views

Author

Tilman Piesk, Apr 09 2012

Keywords

Comments

Name could also be "Triangle of multinomial coefficients, read by rows (version 4)", compare A036040, A080575, A178867. The latter and this one differ only in the order of columns.
The rows are counted from 1, the columns from 0.
Row lengths: 1,2,3,5,7,11... (partition numbers A000041)
Row sums: 1,2,5,15,52,203... (Bell numbers A000110)
Row maxima: 1,1,3,6,15,60,210,840,3780,12600,69300,415800... (A102356)
Distinct entries per row: 1,1,2,4,4,7,7,13,17,23,26,40... (A102465)
Rightmost columns are those from Pascal's triangle A007318 without the second one (i.e. triangle A184049). The other columns - (always?) without a 1 at the top - are multiples of these columns from Pascal's triangle; so actually only the top elements of each column are needed to calculate the other entries; these top elements are in A211360. (The top elements of the related triangle A178867 are in A178866.)

Crossrefs

A255404 Number of different integer partitions of n that produce the maximum number of set partitions for a set of cardinality n.

Original entry on oeis.org

1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 4, 3, 2, 1, 4, 2, 1, 2, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 1, 2, 2, 1, 2, 2, 1, 1, 1, 4, 6, 4, 1, 2, 1, 5, 5, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 5, 2, 2, 1, 1, 4, 1, 1, 2, 3, 1, 8, 2, 1, 1, 3, 1, 1, 1, 3, 1, 1, 3, 1, 6, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 3, 2, 1, 1, 1, 1
Offset: 0

Views

Author

Andrei Cretu, Feb 22 2015

Keywords

Comments

If n=Sum_i[n_i], the number of set partitions can be written as sp=n!/Prod_i,j(n_i!m_j!) where m_j is the multiplicity of the integer j in the n_i's. For certain integers, this number is maximized by more than one partition.

Examples

			For n=9, {1,1,2,2,3} maximizes the number of set partitions, while for n=10, this number is maximized by {1,2,3,4}, {1,1,2,3,3}, {1,2,2,2,3} and {1,1,1,2,2,3}.
		

Crossrefs

Programs

  • Mathematica
    Prod[l_] := Apply[Times, Map[#! &, l]]*
        Apply[Times, Map[Count[l, #]! &, Range[Max[Length[l]]]]]
    b[n_] := (Min[Map[Prod, IntegerPartitions[n]]])
    a[n_] := Count[Map[Prod, IntegerPartitions[n]], b[n]]
    Table[a[n], {n, 0, 20}] (* after A102356 *)

Extensions

More terms from Alois P. Heinz, Feb 25 2015

A333305 Irregular array read by rows, a refinement of A256894.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 3, 1, 1, 1, 1, 3, 3, 1, 4, 3, 5, 1, 6, 1, 1, 1, 1, 4, 6, 4, 1, 5, 10, 9, 8, 7, 1, 10, 15, 9, 1, 10, 1, 1, 1, 1, 5, 10, 10, 5, 1, 6, 15, 14, 10, 35, 16, 15, 9, 1, 15, 60, 19, 15, 33, 12, 1, 20, 45, 14, 1, 15, 1, 1
Offset: 0

Views

Author

Peter Luschny, May 19 2020

Keywords

Examples

			Irregular table (the refinement is indicated by round brackets) starts:
[0] [1]
[1] [1, 1]
[2] [1, (1, 1), 1]
[3] [1, (1, 2, 1), (3, 1), 1]
[4] [1, (1, 3, 3, 1), (4, 3, 5, 1), (6, 1), 1]
[5] [1, (1, 4, 6, 4, 1), (5, 10, 9, 8, 7, 1), (10, 15, 9, 1), (10, 1), 1]
[6] [1, (1, 5, 10, 10, 5, 1), (6, 15, 14, 10, 35, 16, 15, 9, 1), (15, 60, 19, 15,
     33, 12, 1), (20, 45, 14, 1), (15, 1), 1]
		

Crossrefs

Cf. A000070 (length of rows), A102356 (max in rows), A186021 (sum of rows).
Cf. A256894.

Programs

  • SageMath
    def BellBlocks(n):
        R = InfinitePolynomialRing(ZZ, 'v') # Thanks to F. Chapoton.
        V = R.gen()
        @cached_function
        def T(n, k):
            if k == 0: return V[0]^n
            return sum(binomial(n-1, j-1)*V[j]*T(n-j, k-1) for j in (0..n-k+1))
        P = (T(n, k) for k in (0..n))
        return flatten([p.coefficients() for p in P])
    for n in (0..8): print(BellBlocks(n))
Showing 1-7 of 7 results.