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A173155
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a(n) = binomial(n + 5, 5) * 8^n.
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5
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1, 48, 1344, 28672, 516096, 8257536, 121110528, 1660944384, 21592276992, 268703891456, 3224446697472, 37520834297856, 425236122042368, 4710307813392384, 51140484831117312, 545498504865251328, 5727734301085138944, 59298896293587320832, 606166495445559279616
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OFFSET
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0,2
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COMMENTS
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With a different offset, number of n-permutations (n>=5) of 9 objects: p, r, s, t, u, v, z, x, y with repetition allowed, containing exactly five (5) u's.
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LINKS
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FORMULA
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a(n) = C(n + 5, 5)*8^n, n>=0.
Sum_{n>=0} 1/a(n) = 96040*log(8/7) - 38470/3.
Sum_{n>=0} (-1)^n/a(n) = 262440*log(9/8) - 30910. (End)
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MATHEMATICA
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Table[Binomial[n + 5, 5]*8^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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