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A057151
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Number of square binary matrices with n ones, with no zero rows or columns, up to row and column permutation.
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15
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1, 1, 2, 4, 8, 18, 41, 102, 252, 666, 1789, 5031, 14486, 43280, 132777, 420267, 1366307, 4566966, 15661086, 55081118, 198425478, 731661754, 2758808581, 10629386376, 41814350148, 167830018952, 686822393793, 2864024856054, 12162059027416, 52564545391789
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OFFSET
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1,3
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COMMENTS
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Number of square binary matrices with n ones and with no zero rows or columns is A104602(n). - Vladeta Jovovic, Mar 25 2006
Also the number of non-isomorphic square set multipartitions (multisets of sets) of weight n. A multiset partition or hypergraph is square if its length (number of blocks or edges) is equal to its number of vertices. The weight of a multiset partition is the sum of sizes of its parts. - Gus Wiseman, Nov 16 2018
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LINKS
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EXAMPLE
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There are 666 square binary matrices with 10 ones, with no zero rows or columns, up to row and column permutation: 33 of size 4 X 4, 248 of size 5 X 5, 288 of size 6 X 6, 79 of size 7 X 7, 15 of size 8 X 8, 2 of size 9 X 9 and 1 of size 10 X 10. Cf. A057150.
Non-isomorphic representatives of the a(1) = 1 through a(6) = 18 square set multipartitions:
{1} {1}{2} {2}{12} {12}{12} {1}{23}{23} {12}{13}{23}
{1}{2}{3} {1}{1}{23} {2}{13}{23} {1}{23}{123}
{1}{3}{23} {2}{3}{123} {13}{23}{23}
{1}{2}{3}{4} {3}{13}{23} {3}{23}{123}
{3}{3}{123} {1}{1}{1}{234}
{1}{2}{2}{34} {1}{1}{24}{34}
{1}{2}{4}{34} {1}{1}{4}{234}
{1}{2}{3}{4}{5} {1}{2}{34}{34}
{1}{3}{24}{34}
{1}{3}{4}{234}
{1}{4}{24}{34}
{1}{4}{4}{234}
{2}{4}{12}{34}
{3}{4}{12}{34}
{4}{4}{12}{34}
{1}{2}{3}{3}{45}
{1}{2}{3}{5}{45}
{1}{2}{3}{4}{5}{6}
(End)
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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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