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 1-5 of 5 results.

A364128 Decimal expansion of a constant related to A053529 and A179973.

Original entry on oeis.org

4, 4, 3, 2, 3, 8, 9, 5, 4, 7, 3, 0, 9, 2, 8, 5, 0, 9, 4, 0, 7, 7, 7, 5, 1, 2, 0, 7, 2, 8, 3, 3, 1, 8, 5, 1, 5, 0, 2, 0, 7, 2, 1, 9, 2, 4, 3, 9, 1, 5, 3, 0, 8, 7, 0, 7, 7, 6, 2, 9, 2, 8, 7, 8, 5, 3, 4, 5, 9, 1, 5, 9, 1, 4, 4, 7, 8, 7, 3, 5, 9, 3, 2, 5, 5, 7, 6, 1, 1, 6, 9, 2, 9, 1, 3, 8, 2, 8, 7, 1, 6, 4, 8, 5, 8, 8
Offset: 0

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Author

Alois P. Heinz, Jul 09 2023

Keywords

Comments

The digits of this constant are also the final digits of A179973(n) and of the n-th partial sum of A053529 for n -> oo, read from right.

Examples

			0.443238954730928509407775120728331851502072192439153087... .
		

Crossrefs

Formula

Equals lim_{n->oo} A004086(A179973(n))/10^A055642(A179973(n)).
Equals lim_{n->oo} A004086(s(n))/10^A055642(s(n)) with s(n) = Sum_{j=0..n} A053529(j).

A362362 Number of permutations of [n] such that each cycle contains its length as an element.

Original entry on oeis.org

1, 1, 1, 3, 8, 36, 174, 1104, 7440, 62640, 545040, 5649840, 60681600, 748621440, 9518342400, 136758585600, 2009451628800, 32848492723200, 549241915622400, 10066913176320000, 188293339922688000, 3832031198451456000, 79291640831090688000, 1771146970953744384000
Offset: 0

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Author

Alois P. Heinz, Jul 05 2023

Keywords

Comments

The cycle lengths are distinct as a consequence of the definition.

Examples

			a(3) = 3: (123), (132), (1)(23).
a(4) = 8: (1234), (1243), (1324), (1342), (1423), (1432), (1)(234), (1)(243).
		

Crossrefs

Programs

  • Maple
    a:= n-> add((n-nops(p))!, p=select(l-> nops(l)=
            nops({l[]}), combinat[partition](n))):
    seq(a(n), n=0..24);
    # second Maple program:
    b:= proc(n, i, p) option remember; `if`(i*(i+1)/2 b(n$3):
    seq(a(n), n=0..24);
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[i*(i + 1)/2 < n, 0, If[n == 0, p!, b[n, i - 1, p] + b[n - i, Min[n - i, i - 1], p - 1]]];
    a[n_] := b[n, n, n];
    Table[a[n], {n, 0, 24}] (* Jean-François Alcover, Nov 15 2023, from second Maple program *)

A327711 Sum of multinomials M(n-k; p_1-1, ..., p_k-1), where p = (p_1, ..., p_k) ranges over all partitions of n (k is a partition length).

Original entry on oeis.org

1, 1, 2, 3, 6, 10, 27, 55, 171, 475, 1555, 4915, 20023, 68243, 288024, 1213828, 5435935, 23966970, 121432923, 578757824, 3130381590, 16427772974, 91877826663, 519546134163, 3199523135912, 18868494152257, 120274458082095, 772954621249540, 5219747666882153
Offset: 0

Views

Author

Alois P. Heinz, Sep 22 2019

Keywords

Comments

Number of partitions of [n] whose block sizes are nondecreasing when blocks are ordered by their minima and these minima are {1..k} (for some k <= n). a(5) = 10: 12345, 13|245, 14|235, 15|234, 1|2345, 1|24|35, 1|25|34, 1|2|345, 1|2|3|45, 1|2|3|4|5.

Crossrefs

Programs

  • Maple
    with(combinat):
    a:= n-> add(multinomial(n-nops(p), map(
        x-> x-1, p)[], 0), p=partition(n)):
    seq(a(n), n=0..28);
    # second Maple program:
    b:= proc(n, i, p) option remember; `if`(n=0, p!, `if`(i<2, 0,
          b(n, i-1, p)) +b(n-i, min(n-i, i), p-1)/(i-1)!)
        end:
    a:= n-> b(n$3):
    seq(a(n), n=0..28);
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[n == 0, p!, If[i < 2, 0, b[n, i - 1, p]] + b[n - i, Min[n - i, i], p - 1]/(i - 1)!];
    a[n_] := b[n, n, n];
    a /@ Range[0, 28] (* Jean-François Alcover, May 01 2020, from 2nd Maple program *)

A179972 Irregular table T(n,k) = A178886(n,k)/A048996(n,k) read by rows.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 6, 2, 2, 1, 1, 24, 6, 6, 2, 2, 1, 1, 120, 24, 24, 24, 6, 6, 6, 2, 2, 1, 1, 720, 120, 120, 120, 24, 24, 24, 24, 6, 6, 6, 2, 2, 1, 1, 5040, 720, 720, 720, 720, 120, 120, 120, 120, 120, 24, 24, 24, 24, 24, 6, 6, 6, 2, 2, 1, 1, 40320
Offset: 1

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Author

Alford Arnold, Aug 04 2010

Keywords

Comments

Row n has A000041(n) terms.
Consider the five partitions of the number 4:
4 3+1 2+2 2+1+1 and 1+1+1+1
rewriting as 4000 3100 2200 2110 and 1111
then a(n) counts the ways that the zeros can be permuted:
6,2,2,1,1
agreeing with the factorial of the difference between A036042 and A036043.

Examples

			Row four of A178886 begins: 6 4 2 3 1
Row four of A048996 begins: 1 2 1 3 1
so,
Row four of A179972 begins: 6 2 2 1 1
Triangle T(n,k) begins:
    1;
    1,  1;
    2,  1,  1;
    6,  2,  2,  1, 1;
   24,  6,  6,  2, 2, 1, 1;
  120, 24, 24, 24, 6, 6, 6, 2, 2, 1, 1;
  ...
		

Crossrefs

Cf. A178886, A048996, A036042, A036043, A179973 (row sums).

Formula

T(n,k) = ( A036042(n,k) - A036043(n,k))!.
T(n,k) = n!/A178888(n,k). - R. J. Mathar, Mar 03 2011

A179974 Triangle read by rows: T(n,k) = (n-A049085(n,k))! in columns 1<=k<=A000041(n), rows n>=1.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 6, 1, 1, 2, 2, 6, 6, 24, 1, 1, 2, 6, 2, 6, 24, 6, 24, 24, 120, 1, 1, 2, 6, 2, 6, 24, 24, 6, 24, 120, 24, 120, 120, 720, 1, 1, 2, 6, 24, 2, 6, 24, 24, 120, 6, 24, 120, 120, 720, 24, 120, 720, 120, 720, 720, 5040, 1, 1, 2, 6, 24, 2, 6, 24, 120, 24, 120, 720, 6, 24, 120, 120, 720, 720, 24, 120, 720, 720, 5040, 120, 720, 5040
Offset: 1

Views

Author

Alford Arnold, Aug 05 2010

Keywords

Comments

Since A049085 is a resortment of A036043 both A179972 and A179974 have row sums equal to A179973.

Examples

			Triangle begins
1;
1,1;
1,1,2;
1,1,2,2,6;
1,1,2,2,6,6,24;
1,1,2,6,2,6,24,6,24,24,120;
1,1,2,6,2,6,24,24,6,24,120,24,120,120,720;
1,1,2,6,24,2,6,24,24,120,6,24,120,120,720,24,120,720,120,720,720,5040;
1,1,2,6,24,2,6,24,120,24,120,720,6,24,120,120,720,720,24,120,720,720,5040,120,720,5040,720,5040,5040,40320,
		

Crossrefs

Cf. A000041 (row lengths), A179973 (row sums), A036042, A049085 (max part).
Showing 1-5 of 5 results.