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Search: id:A058389
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| A058389 |
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Number of 3 X 3 matrices with nonnegative integer entries and all row sums equal to n, up to row and column permutation. |
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+0
7
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| 1, 3, 14, 44, 129, 316, 714, 1452, 2775, 4963, 8478, 13838, 21827, 33306, 49504, 71754, 101871, 141807, 194128, 261570, 347633, 456026, 591384, 758596, 963657, 1212861, 1513806, 1874440, 2304225, 2813030, 3412466, 4114608, 4933519
(list; graph; listen)
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OFFSET
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0,2
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LINKS
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V. Jovovic, Illustration of initial terms
V. Jovovic, Number of m x m nonnegative integer matrices with all row sums equal to n, up to row and column permutation.
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FORMULA
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a(n)=1/6*(C(C(n + 2, 2) + 2, 3) + 3/2*floor((n + 2)/2)*(C(n + 2, 2) - floor((n + 2)/2)) + 3*C(floor((n + 2)/2) + 2, 3) + 2*floor(C(n + 2, 2)/3) + 2*C(C(n + 2, 2) - 3*floor(C(n + 2, 2)/3) + 2, 3)).
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CROSSREFS
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Cf. A002817, A052282, A058390-A058392.
Cf. A050535, A050913, A058783, A058390, A058784, A058785, A058391, A058392, A001501, A058528
Adjacent sequences: A058386 A058387 A058388 this_sequence A058390 A058391 A058392
Sequence in context: A124650 A063903 A115005 this_sequence A059672 A032316 A032225
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KEYWORD
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nice,nonn,easy
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Nov 24 2000
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EXTENSIONS
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More terms from Marc LeBrun (mlb(AT)well.com), Dec 11 2000
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