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A120733
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Number of matrices with nonnegative integer entries and without zero rows or columns such that sum of all entries is equal to n.
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61
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1, 1, 5, 33, 281, 2961, 37277, 546193, 9132865, 171634161, 3581539973, 82171451025, 2055919433081, 55710251353953, 1625385528173693, 50800411296363617, 1693351638586070209, 59966271207156833313, 2248276994650395873861, 88969158875611127548481
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OFFSET
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0,3
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COMMENTS
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The number of such matrices up to rows/columns permutations are given in A007716.
Dimensions of the graded components of the Hopf algebra MQSym (Matrix quasi-symmetric functions). - Jean-Yves Thibon (jyt(AT)univ-mlv.fr), Oct 23 2006
Number of cells in the two-sided Coxeter complex of the symmetric group. Inclusion of faces corresponds to refinement of matrices, see Section 6 of Petersen paper. The number of cells in the type B analog is given by A275787.
Also known as "two-way contingency tables" in the Diaconis-Gangolli reference. (End)
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LINKS
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Giulio Cerbai and Anders Claesson, Caylerian polynomials, arXiv:2310.01270 [math.CO], 2023. Mentions this sequence.
P. Diaconis and A. Gangolli, Rectangular arrays with fixed margins, Discrete probability and algorithms (Minneapolis, MN, 1993), 15-41, IMA Vol. Math. Appl., 72, Springer, New York, 1995.
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FORMULA
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a(n) = (1/n!)*Sum_{k=0..n} (-1)^(n-k)*Stirling1(n,k)*A000670(k)^2.
G.f.: Sum_{m>=0,n>=0} Sum_{j=0..n} (-1)^(n-j)*C(n,j)*((1-x)^(-j)-1)^m.
a(n) = Sum_{r>=0,s>=0} binomial(r*s+n-1,n)/2^(r+s+2).
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EXAMPLE
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a(2) = 5:
[1 0] [0 1] [1] [1 1] [2]
[0 1] [1 0] [1]
The a(3) = 33 matrices:
[3][21][12][111]
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[2][20][11][11][110][101][1][10][10][100][02][011][01][01][010][001]
[1][01][10][01][001][010][2][11][02][011][10][100][20][11][101][110]
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[1][10][10][10][100][100][01][01][010][01][010][001][001]
[1][10][01][01][010][001][10][10][100][01][001][100][010]
[1][01][10][01][001][010][10][01][001][10][100][010][100]
(End)
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MAPLE
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t1 := M -> add( add( add( (-1)^(n-j)*binomial(n, j)*((1-x)^(-j)-1)^m, j=0..n), n=0..M), m=0..M); s := series(t1(20), x, 20); gfun[seriestolist](%); # N. J. A. Sloane, Jan 14 2009
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MATHEMATICA
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a[n_] := Sum[2^(-2-r-s)*Binomial[n+r*s-1, n], {r, 0, Infinity}, {s, 0, Infinity}]; Table[Print[an = a[n]]; an, {n, 0, 19}] (* Jean-François Alcover, May 15 2012, after Vladeta Jovovic *)
Flatten[{1, Table[1/n!*Sum[(-1)^(n-k)*StirlingS1[n, k]*Sum[m!*StirlingS2[k, m], {m, k}]^2, {k, n}], {n, 20}]}] (* Vaclav Kotesovec, May 07 2014 *)
multsubs[set_, k_]:=If[k==0, {{}}, Join@@Table[Prepend[#, set[[i]]]&/@multsubs[Drop[set, i-1], k-1], {i, Length[set]}]]; Table[Length[Select[multsubs[Tuples[Range[n], 2], n], And[Union[First/@#]==Range[Max@@First/@#], Union[Last/@#]==Range[Max@@Last/@#]]&]], {n, 5}] (* Gus Wiseman, Nov 14 2018 *)
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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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