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Search: id:A056037
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| A056037 |
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Number of 6x6 binary matrices with n ones, with no zero rows or columns, up to row and column permutation. |
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+0
5
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| 1, 2, 15, 69, 288, 840, 2144, 4488, 8317, 13160, 18636, 23078, 25856, 25623, 23187, 18713, 13932, 9288, 5816, 3256, 1767, 858, 419, 180, 88, 34, 16, 6, 3, 1, 1
(list; graph; listen)
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OFFSET
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6,2
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COMMENT
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Sum_{k=0..36} a(n)=A054976(6).
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FORMULA
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G.f. : Z(S_6 X S_6; x_1, x_2, ...)-2*Z(S_6 X S_5; x_1, x_2, ...)+Z(S_5 X S_5; x_1, x_2, ...) if we replace x_i by 1+x^i, where Z(S_i X S_j; x_1, x_2, ...) is cycle index of Cartesian product of symmetric groups S_i and S_j of degree i and j, respectively.
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CROSSREFS
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Cf. A052370.
Sequence in context: A055206 A146757 A091135 this_sequence A125903 A007232 A099743
Adjacent sequences: A056034 A056035 A056036 this_sequence A056038 A056039 A056040
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KEYWORD
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fini,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 04 2000
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