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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.

A309973 Number T(n,k) of colored integer partitions of n using all colors of a k-set such that parts i have distinct color patterns in arbitrary order and each pattern for a part i has i colors in (weakly) increasing order; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 1, 3, 0, 2, 6, 10, 0, 2, 21, 42, 47, 0, 3, 42, 177, 264, 246, 0, 4, 90, 619, 1746, 2095, 1602, 0, 5, 176, 1809, 7556, 16085, 16608, 11481, 0, 6, 348, 5211, 32621, 100030, 171480, 154385, 95503, 0, 8, 640, 13961, 120964, 522890, 1262832, 1842659, 1503232, 871030
Offset: 0

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Author

Alois P. Heinz, Sep 21 2019

Keywords

Examples

			T(3,1) = 2: 3aaa, 2aa1a.
T(3,2) = 6: 3aab, 3abb, 2aa1b, 2ab1a, 2ab1b, 2bb1a.
T(3,3) = 10: 3abc, 2ab1c, 2ac1b, 2bc1a, 1a1b1c, 1a1c1b, 1b1a1c, 1b1c1a, 1c1a1b, 1c1b1a.
Triangle T(n,k) begins:
  1;
  0, 1;
  0, 1,   3;
  0, 2,   6,   10;
  0, 2,  21,   42,    47;
  0, 3,  42,  177,   264,    246;
  0, 4,  90,  619,  1746,   2095,   1602;
  0, 5, 176, 1809,  7556,  16085,  16608,  11481;
  0, 6, 348, 5211, 32621, 100030, 171480, 154385, 95503;
  ...
		

Crossrefs

Columns k=0-2 give: A000007, A000009 (for n>0), A327890.
Main diagonal gives A005651.
Row sums give A327679.
T(2n,n) gives A327681.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(b(n-i*j, min(n-i*j, i-1), k)*
           binomial(binomial(k+i-1, i), j)*j!, j=0..n/i)))
        end:
    T:= (n, k)-> add(b(n$2, i)*(-1)^(k-i)*binomial(k, i), i=0..k):
    seq(seq(T(n, k), k=0..n), n=0..12);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n==0, 1, If[i<1, 0, Sum[b[n - i j, Min[n - i j, i-1], k] Binomial[Binomial[k+i-1, i], j] j!, {j, 0, n/i}]]];
    T[n_, k_] := Sum[b[n, n, i] (-1)^(k - i) Binomial[k, i], {i, 0, k}];
    Table[T[n, k], {n, 0, 12}, {k, 0, n}] // Flatten (* Jean-François Alcover, May 29 2020, after Maple *)

Formula

Sum_{k=1..n} k * T(n,k) = A327680(n).