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A047918
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Triangular array read by rows: a(n,k) = Sum_{d|k} mu(d)*U(n,k/d) if k|n else 0, where U(n,k) = A047916(n,k) (1<=k<=n).
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7
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1, 2, 0, 6, 0, 0, 8, 0, 0, 16, 20, 0, 0, 0, 100, 12, 24, 36, 0, 0, 648, 42, 0, 0, 0, 0, 0, 4998, 32, 32, 0, 320, 0, 0, 0, 39936, 54, 0, 270, 0, 0, 0, 0, 0, 362556, 40, 160, 0, 0, 3800, 0, 0, 0, 0, 3624800, 110, 0, 0, 0, 0, 0, 0, 0, 0, 0, 39916690, 48, 96
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OFFSET
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1,2
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REFERENCES
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J. E. A. Steggall, On the numbers of patterns which can be derived from certain elements, Mess. Math., 37 (1907), 56-61.
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LINKS
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MATHEMATICA
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U[n_, k_] := If[ Divisible[n, k], EulerPhi[n/k]*(n/k)^k*k!, 0]; a[n_, k_] := Sum[ If[ Divisible[n, k], MoebiusMu[d]*U[n, k/d], 0], {d, Divisors[k]}]; Flatten[ Table[ a[n, k], {n, 1, 12}, {k, 1, n}]] (* Jean-François Alcover, May 04 2012 *)
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PROG
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(Haskell)
a047918 n k = sum [a008683 (fromIntegral d) * a047916 n (k `div` d) |
mod n k == 0, d <- [1..k], mod k d == 0]
a047918_row n = map (a047918 n) [1..n]
a047918_tabl = map a047918_row [1..]
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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