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A140907
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Number of 3 X 7 matrices with elements in 0..n with each row and each column in nondecreasing order. 3,7,n can be permuted, see formula.
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1
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1, 120, 4950, 108900, 1557270, 16195608, 131589315, 877262100, 4971151900, 24584605760, 108284013552, 431621592480, 1577078895600, 5337805492800, 16880809870980, 50245234086564, 141622596077325, 379998709805000, 974996689631250, 2401570793407500
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OFFSET
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0,2
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LINKS
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FORMULA
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(empirical) set p,q,r to n,7,3 (in any order) in s=p+q+r-1; a(n) = product {i in 0..r-1} (binomial(s,p+i)*i!/(s-i)^(r-i-1))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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