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Search: id:A056079
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| A056079 |
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Number of 7x7 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, 79, 420, 1744, 6197, 18715, 50042, 118121, 250025, 475791, 820987, 1287695, 1845875, 2423114, 2923474, 3246721, 3327677, 3150758, 2761802, 2242711, 1690526, 1183725, 771951, 469281, 267108, 142542, 71844, 34271, 15685
(list; graph; listen)
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OFFSET
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7,2
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COMMENT
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Sum_{k=0..49} a(n)=A054976(7).
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FORMULA
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G.f. : Z(S_7 X S_7; x_1, x_2, ...)-2*Z(S_7 X S_6; x_1, x_2, ...)+Z(S_6 X S_6; 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. A053304.
Sequence in context: A099743 A102289 A041243 this_sequence A036239 A109725 A057152
Adjacent sequences: A056076 A056077 A056078 this_sequence A056080 A056081 A056082
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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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