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.

A116540 Number of zero-one matrices with n ones and no zero rows or columns, up to permutation of rows.

Original entry on oeis.org

1, 1, 3, 10, 41, 192, 1025, 6087, 39754, 282241, 2159916, 17691161, 154192692, 1423127819, 13851559475, 141670442163, 1517880400352, 16989834719706, 198191448685735, 2404300796114642, 30273340418567819, 394948562421362392, 5330161943597341380, 74307324695105372519
Offset: 0

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Author

Vladeta Jovovic, Mar 27 2006

Keywords

Comments

Also number of normal set multipartitions of weight n. These are defined as multisets of sets that together partition a normal multiset of weight n, where a multiset is normal if it spans an initial interval of positive integers. Set multipartitions are involved in the expansion of elementary symmetric functions in terms of augmented monomial symmetric functions. - Gus Wiseman, Oct 22 2015

Examples

			The a(3) = 10 normal set multipartitions are: {1,1,1}, {1,12}, {1,1,2}, {2,12}, {1,2,2}, {123}, {1,23}, {2,13}, {3,12}, {1,2,3}.
		

Crossrefs

Row sums of A327117.

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)+j-1, j), j=0..n/i)))
        end:
    a:= n-> add(add(b(n$2, i)*(-1)^(k-i)*binomial(k, i), i=0..k), k=0..n):
    seq(a(n), n=0..24);  # Alois P. Heinz, Sep 13 2019
  • Mathematica
    MSOSA[s_List] :=
      MSOSA[s] = If[Length[s] === 0, {{}}, Module[{sbs, fms},
         sbs = Rest[Subsets[Union[s]]];
         fms =
          Function[r,
            Append[#, r] & /@
             MSOSA[Fold[DeleteCases[#1, #2, {1}, 1] &, s, r]]] /@ sbs;
         Select[Join @@ fms, OrderedQ]
         ]];
    mmallnorm[n_Integer] :=
      Function[s, Array[Count[s, y_ /; y <= #] + 1 &, n]] /@
       Subsets[Range[n - 1] + 1];
    Array[Plus @@ Length /@ MSOSA /@ mmallnorm[#] &, 9]
    (* Gus Wiseman, Oct 22 2015 *)
  • PARI
    R(n, k)={Vec(-1 + 1/prod(j=1, k, (1 - x^j + O(x*x^n))^binomial(k, j) ))}
    seq(n) = {concat([1], sum(k=1, n, R(n, k)*sum(r=k, n, binomial(r, k)*(-1)^(r-k)) ))} \\ Andrew Howroyd, Sep 23 2023

Extensions

a(0)=1 prepended and more terms added by Alois P. Heinz, Sep 13 2019