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A116540
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Number of zero-one matrices with n ones and no zero rows or columns, up to permutation of rows.
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40
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1, 1, 3, 10, 41, 192, 1025, 6087, 39754, 282241, 2159916, 17691161, 154192692, 1423127819, 13851559475, 141670442163, 1517880400352, 16989834719706, 198191448685735, 2404300796114642, 30273340418567819, 394948562421362392, 5330161943597341380, 74307324695105372519
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OFFSET
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0,3
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COMMENTS
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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
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LINKS
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EXAMPLE
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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}.
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MAPLE
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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):
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MATHEMATICA
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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]
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PROG
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(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
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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