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 1-3 of 3 results.

A077365 Sum of products of factorials of parts in all partitions of n.

Original entry on oeis.org

1, 1, 3, 9, 37, 169, 981, 6429, 49669, 430861, 4208925, 45345165, 536229373, 6884917597, 95473049469, 1420609412637, 22580588347741, 381713065286173, 6837950790434781, 129378941557961565, 2578133190722896861, 53965646957320869469, 1183822028149936497501
Offset: 0

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Author

Vladeta Jovovic, Nov 30 2002

Keywords

Comments

Row sums of arrays A069123 and A134133. Row sums of triangle A134134.

Examples

			The partitions of 4 are 4, 3+1, 2+2, 2+1+1, 1+1+1+1, the corresponding products of factorials of parts are 24,6,4,2,1 and their sum is a(4) = 37.
1 + x + 3 x^2 + 9 x^3 + 37 x^4 + 169 x^5 + 981 x^6 + 6429 x^7 + 49669 x^8 + ...
		

Crossrefs

Cf. A051296 (with compositions instead of partitions).

Programs

  • Maple
    b:= proc(n, i, j) option remember;
          `if`(n=0, 1, `if`(i<1, 0, b(n, i-1, j)+
          `if`(i>n, 0, j^i*b(n-i, i, j+1))))
        end:
    a:= n-> b(n$2, 1):
    seq(a(n), n=0..40);  # Alois P. Heinz, Aug 03 2013
    # second Maple program:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
           b(n, i-1)+`if`(i>n, 0, b(n-i, i)*i!)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..30);  # Alois P. Heinz, May 11 2016
  • Mathematica
    Table[Plus @@ Map[Times @@ (#!) &, IntegerPartitions[n]], {n, 0, 20}] (* Olivier Gérard, Oct 22 2011 *)
    a[ n_] := If[ n < 0, 0, Plus @@ Times @@@ (IntegerPartitions[ n] !)] (* Michael Somos, Feb 09 2012 *)
    nmax=20; CoefficientList[Series[Product[1/(1-k!*x^k),{k,1,nmax}],{x,0,nmax}],x] (* Vaclav Kotesovec, Mar 14 2015 *)
    b[n_, i_, j_] := b[n, i, j] = If[n==0, 1, If[i<1, 0, b[n, i-1, j] + If[i>n, 0, j^i*b[n-i, i, j+1]]]]; a[n_] := b[n, n, 1]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Oct 12 2015, after Alois P. Heinz *)
  • PARI
    N=66; q='q+O('q^N);
    gf= 1/prod(n=1,N, (1-n!*q^n) );
    Vec(gf)
    /* Joerg Arndt, Oct 06 2012 */

Formula

G.f.: 1/Product_{m>0} (1-m!*x^m).
Recurrence: a(n) = 1/n*Sum_{k=1..n} b(k)*a(n-k), where b(k) = Sum_{d divides k} d*d!^(k/d).
a(n) ~ n! * (1 + 1/n + 3/n^2 + 12/n^3 + 67/n^4 + 457/n^5 + 3734/n^6 + 35741/n^7 + 392875/n^8 + 4886114/n^9 + 67924417/n^10), for coefficients see A256125. - Vaclav Kotesovec, Mar 14 2015
G.f.: exp(Sum_{k>=1} Sum_{j>=1} (j!)^k*x^(j*k)/k). - Ilya Gutkovskiy, Jun 18 2018

Extensions

Unnecessarily complicated mma code deleted by N. J. A. Sloane, Sep 21 2009

A134133 A certain partition array in Abramowitz-Stegun order (A-St order).

Original entry on oeis.org

1, 2, 1, 6, 2, 1, 24, 6, 4, 2, 1, 120, 24, 12, 6, 4, 2, 1, 720, 120, 48, 36, 24, 12, 8, 6, 4, 2, 1, 5040, 720, 240, 144, 120, 48, 36, 24, 24, 12, 8, 6, 4, 2, 1, 40320, 5040, 1440, 720, 576, 720, 240, 144, 96, 72, 120, 48, 36, 24, 16, 24, 12, 8, 6, 4, 2, 1, 362880, 40320, 10080
Offset: 1

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Author

Wolfdieter Lang, Oct 12 2007

Keywords

Comments

The sequence of row lengths is A000041 (partition numbers) [1, 2, 3, 5, 7, 11, 15, 22, 30, 42,...].
Partition number array M_3(2)= A130561 divided by partition number array M_3 = M_3(1) = A036040.

Examples

			[1], [2,1], [6,2,1], [24,6,4,2,1], [120,24,12,6,4,2,1], ...
		

Crossrefs

With another ordering of the partitions this becomes A069123.
Cf. A134134 (triangle obtained by summing same m numbers).

Formula

a(n,k) = A130561(n,k)/A036040(n,k) (division of partition arrays M_3(2) by M_3).
a(n,k) = product(j!^e(n,k,j),j=1..n) with the exponent e(n,k,j) of j in the k-th partition of n in the A-St ordering of the partitions of n.

A333144 Irregular triangle where row n lists the product of the factorials of the exponentials of the partitions of n and the partitions are enumerated in canonical order.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 6, 1, 1, 2, 2, 24, 1, 1, 1, 2, 2, 6, 120, 1, 1, 1, 2, 2, 1, 6, 6, 4, 24, 720, 1, 1, 1, 2, 1, 1, 6, 2, 2, 2, 24, 6, 12, 120, 5040, 1, 1, 1, 2, 1, 1, 6, 2, 1, 2, 2, 24, 2, 4, 2, 6, 120, 24, 12, 48, 720, 40320
Offset: 0

Views

Author

Peter Luschny, Apr 10 2020

Keywords

Comments

By 'canonical order' we understand the graded reverse lexicographic order (the default order of Mathematica and SageMath).

Examples

			The irregular table starts:
[0] [1]
[1] [1]
[2] [1, 2]
[3] [1, 1, 6]
[4] [1, 1, 2, 2, 24]
[5] [1, 1, 1, 2, 2, 6, 120]
[6] [1, 1, 1, 2, 2, 1, 6, 6, 4, 24, 720]
[7] [1, 1, 1, 2, 1, 1, 6, 2, 2, 2, 24, 6, 12, 120, 5040]
		

Crossrefs

Row sums are A161779.
Cf. A069123.

Programs

  • SageMath
    def A333144row(n):
        return [product(factorial(expo) for expo in partition.to_exp()) for partition in Partitions(n)]
    for n in (0..9): print(A333144row(n))
Showing 1-3 of 3 results.