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A368524
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a(n) = Sum_{k=1..n} k^2 * n^(n-k).
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4
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0, 1, 6, 30, 180, 1455, 15666, 213500, 3521736, 68101245, 1508916310, 37661140506, 1045012524348, 31900040161899, 1062139933257690, 38299757176168440, 1486670929792295696, 61800664096000744569, 2738952078516469743678, 128909373997071187219990
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) = [x^n] x * (1+x)/((1-n*x) * (1-x)^3).
a(n) = n * (n+1) * (n^n - n^2 + n - 1)/(n-1)^3 for n > 1.
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PROG
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(PARI) a(n) = sum(k=1, n, k^2*n^(n-k));
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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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