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.

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A346520 Number A(n,k) of partitions of the (n+k)-multiset {0,...,0,1,2,...,k} with n 0's into distinct multisets; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 5, 5, 3, 2, 15, 15, 9, 5, 2, 52, 52, 31, 16, 7, 3, 203, 203, 120, 59, 25, 10, 4, 877, 877, 514, 244, 100, 38, 14, 5, 4140, 4140, 2407, 1112, 442, 161, 56, 19, 6, 21147, 21147, 12205, 5516, 2134, 750, 249, 80, 25, 8, 115975, 115975, 66491, 29505, 11147, 3799, 1213, 372, 111, 33, 10
Offset: 0

Views

Author

Alois P. Heinz, Jul 21 2021

Keywords

Comments

Also number A(n,k) of factorizations of 2^n * Product_{i=1..k} prime(i+1) into distinct factors; A(3,1) = 5: 2*3*4, 4*6, 3*8, 2*12, 24; A(1,2) = 5: 2*3*5, 5*6, 3*10, 2*15, 30.

Examples

			A(2,2) = 9: 00|1|2, 001|2, 1|002, 0|01|2, 0|1|02, 01|02, 00|12, 0|012, 0012.
Square array A(n,k) begins:
  1,  1,   2,   5,   15,    52,   203,    877,    4140, ...
  1,  2,   5,  15,   52,   203,   877,   4140,   21147, ...
  1,  3,   9,  31,  120,   514,  2407,  12205,   66491, ...
  2,  5,  16,  59,  244,  1112,  5516,  29505,  168938, ...
  2,  7,  25, 100,  442,  2134, 11147,  62505,  373832, ...
  3, 10,  38, 161,  750,  3799, 20739, 121141,  752681, ...
  4, 14,  56, 249, 1213,  6404, 36332, 220000, 1413937, ...
  5, 19,  80, 372, 1887, 10340, 60727, 379831, 2516880, ...
  6, 25, 111, 539, 2840, 16108, 97666, 629346, 4288933, ...
  ...
		

Crossrefs

Main diagonal gives A346519.
Antidiagonal sums give A346521.

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 1, add(g(n-j)*add(
         `if`(d::odd, d, 0), d=numtheory[divisors](j)), j=1..n)/n)
        end:
    s:= proc(n) option remember; expand(`if`(n=0, 1,
          x*add(s(n-j)*binomial(n-1, j-1), j=1..n)))
        end:
    S:= proc(n, k) option remember; coeff(s(n), x, k) end:
    b:= proc(n, i) option remember; `if`(n=0, 1,
         `if`(i=0, g(n), add(b(n-j, i-1), j=0..n)))
        end:
    A:= (n, k)-> add(S(k, j)*b(n, j), j=0..k):
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    g[n_] := g[n] = If[n == 0, 1, Sum[g[n - j]*Sum[If[OddQ[d], d, 0], {d, Divisors[j]}], {j, 1, n}]/n];
    s[n_] := s[n] = Expand[If[n == 0, 1, x*Sum[s[n - j]*Binomial[n - 1, j - 1], {j, 1, n}]]];
    S[n_, k_] := S[n, k] = Coefficient[s[n], x, k];
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i == 0, g[n], Sum[b[n - j, i - 1], {j, 0, n}]]];
    A[n_, k_] := Sum[S[k, j]*b[n, j], {j, 0, k}];
    Table[Table[A[n, d - n], {n, 0, d}], {d, 0, 12}] // Flatten (* Jean-François Alcover, Jul 31 2021, after Alois P. Heinz *)

Formula

A(n,k) = A045778(A000079(n)*A070826(k+1)).
A(n,k) = Sum_{j=0..k} Stirling2(k,j)*Sum_{i=0..n} binomial(j+i-1,i)*A000009(n-i).

A346428 Total number of partitions of all n-multisets {0,...,0,1,2,...,j} for 0 <= j <= n.

Original entry on oeis.org

1, 2, 6, 17, 53, 180, 683, 2866, 13219, 66307, 358532, 2074229, 12761831, 83086064, 570017222, 4106269668, 30965072776, 243778358992, 1998878586251, 17034471643814, 150591119435358, 1378657063570498, 13050460812585580, 127553991370245410, 1285578058726241427
Offset: 0

Views

Author

Alois P. Heinz, Jul 16 2021

Keywords

Comments

Also total number of factorizations of 2^(n-j) * Product_{i=1..j} prime(i+1) for 0 <= j <= n; a(2) = 6: 2*2, 4, 2*3, 6, 3*5, 15; a(3) = 17: 2*2*2, 2*4, 8, 2*2*3, 3*4, 2*6, 12, 2*3*5, 5*6, 3*10, 2*15, 30, 3*5*7, 7*15, 5*21, 3*35, 105.

Examples

			a(2) = 6: 00, 0|0, 01, 0|1, 12, 1|2.
a(3) = 17: 000, 0|00, 0|0|0, 001, 00|1, 0|01, 0|0|1, 012, 0|12, 02|1, 01|2, 0|1|2, 123, 1|23, 13|2, 12|3, 1|2|3.
		

Crossrefs

Antidiagonal sums of A346426.

Programs

  • Maple
    s:= proc(n) option remember; expand(`if`(n=0, 1,
          x*add(s(n-j)*binomial(n-1, j-1), j=1..n)))
        end:
    S:= proc(n, k) option remember; coeff(s(n), x, k) end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i=0,
          combinat[numbpart](n), add(b(n-j, i-1), j=0..n)))
        end:
    a:= n-> add(add(S(n-i, j)*b(i, j), j=0..n-i), i=0..n):
    seq(a(n), n=0..25);
  • Mathematica
    s[n_] := s[n] = Expand[If[n == 0, 1,
         x*Sum[s[n - j]*Binomial[n - 1, j - 1], {j, 1, n}]]];
    S[n_, k_] := S[n, k] = Coefficient[s[n], x, k];
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i == 0,
         PartitionsP[n], Sum[b[n - j, i - 1], {j, 0, n}]]];
    a[n_] := Sum[Sum[S[n - i, j]*b[i, j], {j, 0, n - i}], {i, 0, n}];
    Table[a[n], {n, 0, 25}] (* Jean-François Alcover, Mar 12 2022, after Alois P. Heinz *)

Formula

a(n) = Sum_{j=0..n} A346426(n-j,j).
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