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.

A327244 Number T(n,k) of colored compositions of n using all colors of a k-set such that all parts have different color patterns and the patterns for parts i are sorted and have 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, 2, 0, 3, 10, 8, 0, 3, 27, 54, 31, 0, 5, 70, 255, 336, 147, 0, 11, 223, 1222, 2692, 2580, 899, 0, 13, 508, 4467, 15512, 25330, 19566, 5777, 0, 19, 1193, 15540, 78819, 194075, 248976, 160377, 41024, 0, 27, 2822, 52981, 375440, 1303250, 2463534, 2593339, 1430288, 322488
Offset: 0

Views

Author

Alois P. Heinz, Sep 14 2019

Keywords

Examples

			T(3,1) = 3: 3aaa, 2aa1a, 1a2aa.
T(3,2) = 10: 3aab, 3abb, 2aa1b, 2ab1a, 2ab1b, 2bb1a, 1a2ab, 1a2bb, 1b2aa, 1b2ab.
T(3,3) = 8: 3abc, 2ab1c, 2ac1b, 2bc1a, 1a2bc, 1b2ac, 1c2ab, 1a1b1c.
Triangle T(n,k) begins:
  1;
  0,  1;
  0,  1,    2;
  0,  3,   10,     8;
  0,  3,   27,    54,    31;
  0,  5,   70,   255,   336,    147;
  0, 11,  223,  1222,  2692,   2580,    899;
  0, 13,  508,  4467, 15512,  25330,  19566,   5777;
  0, 19, 1193, 15540, 78819, 194075, 248976, 160377, 41024;
  ...
		

Crossrefs

Columns k=0-2 give: A000007, A032020 (for n>0), A327841.
Main diagonal gives A120774.
Row sums give A309670.
T(2n,n) gives A327596.

Programs

  • Maple
    C:= binomial:
    b:= proc(n, i, k, p) option remember; `if`(n=0, p!, `if`(i<1, 0, add(
          b(n-i*j, min(n-i*j, i-1), k, p+j)/j!*C(C(k+i-1,i),j), j=0..n/i)))
        end:
    T:= (n, k)-> add(b(n$2, i, 0)*(-1)^(k-i)*C(k, i), i=0..k):
    seq(seq(T(n, k), k=0..n), n=0..10);
  • Mathematica
    c = Binomial;
    b[n_, i_, k_, p_] := b[n, i, k, p] = If[n == 0, p!, If[i < 1, 0, Sum[b[n - i*j, Min[n - i*j, i-1], k, p+j]/j!*c[c[k + i - 1, i], j], {j, 0, n/i}]]];
    T[n_, k_] := Sum[b[n, n, i, 0]*(-1)^(k-i)*c[k, i], {i, 0, k}];
    Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Apr 28 2020, after Alois P. Heinz *)

Formula

Sum_{k=1..n} k * T(n,k) = A327595(n).