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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.

A292506 Number T(n,k) of multisets of exactly k nonempty binary words with a total of n letters such that no word has a majority of 0's; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 3, 1, 0, 4, 3, 1, 0, 11, 10, 3, 1, 0, 16, 23, 10, 3, 1, 0, 42, 59, 33, 10, 3, 1, 0, 64, 134, 83, 33, 10, 3, 1, 0, 163, 320, 230, 98, 33, 10, 3, 1, 0, 256, 699, 568, 270, 98, 33, 10, 3, 1, 0, 638, 1599, 1451, 738, 291, 98, 33, 10, 3, 1, 0, 1024, 3434, 3439, 1935, 798, 291, 98, 33, 10, 3, 1
Offset: 0

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Author

Alois P. Heinz, Sep 17 2017

Keywords

Examples

			T(4,2) = 10: {1,011}, {1,101}, {1,110}, {1,111}, {01,01}, {01,10}, {01,11}, {10,10}, {10,11}, {11,11}.
Triangle T(n,k) begins:
  1;
  0,   1;
  0,   3,    1;
  0,   4,    3,    1;
  0,  11,   10,    3,   1;
  0,  16,   23,   10,   3,   1;
  0,  42,   59,   33,  10,   3,  1;
  0,  64,  134,   83,  33,  10,  3,  1;
  0, 163,  320,  230,  98,  33, 10,  3,  1;
  0, 256,  699,  568, 270,  98, 33, 10,  3, 1;
  0, 638, 1599, 1451, 738, 291, 98, 33, 10, 3, 1;
  ...
		

Crossrefs

Columns k=0-10 give: A000007, A027306 (for n>0), A316403, A316404, A316405, A316406, A316407, A316408, A316409, A316410, A316411.
Row sums give A292548.
T(2n,n) gives A292549.

Programs

  • Maple
    g:= n-> 2^(n-1)+`if`(n::odd, 0, binomial(n, n/2)/2):
    b:= proc(n, i) option remember; expand(`if`(n=0 or i=1, x^n,
          add(binomial(g(i)+j-1, j)*b(n-i*j, i-1)*x^j, j=0..n/i)))
        end:
    T:= n-> (p-> seq(coeff(p,x,i), i=0..n))(b(n$2)):
    seq(T(n), n=0..12);
  • Mathematica
    g[n_] := 2^(n-1) + If[OddQ[n], 0, Binomial[n, n/2]/2];
    b[n_, i_] := b[n, i] = Expand[If[n == 0 || i == 1, x^n, Sum[Binomial[g[i] + j - 1, j]*b[n - i*j, i - 1]*x^j, {j, 0, n/i}]]];
    T[n_] := Function[p, Table[Coefficient[p, x, i], {i, 0, n}]][b[n, n]];
    Table[T[n], {n, 0, 12}] // Flatten (* Jean-François Alcover, Jun 06 2018, from Maple *)

Formula

G.f.: Product_{j>=1} 1/(1-y*x^j)^A027306(j).