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A173191
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a(n) = binomial(n + 6, 6)*9^n.
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5
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1, 63, 2268, 61236, 1377810, 27280638, 491051484, 8207574804, 129269303163, 1939039547445, 27922169483208, 388371993720984, 5243021915233284, 68965903654222428, 886704475554288360, 11172476391984033336, 138259395350802412533, 1683511461036241140843
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OFFSET
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0,2
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COMMENTS
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Number of n-permutations (n>=6) of 10 objects p, r, q, u, v, w, z, x, y, z with repetition allowed, containing exactly six (6) u's.
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LINKS
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FORMULA
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a(n) = C(n + 6, 6)*9^n.
Sum_{n>=0} 1/a(n) = 1042074/5 - 1769472*log(9/8).
Sum_{n>=0} (-1)^n/a(n) = 5400000*log(10/9) - 2844729/5. (End)
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MAPLE
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MATHEMATICA
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Table[Binomial[n + 6, 6]*9^n, {n, 0, 20}]
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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