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A059381
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Product J_2(i), i=1..n.
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9
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1, 3, 24, 288, 6912, 165888, 7962624, 382205952, 27518828544, 1981355655168, 237762678620160, 22825217147535360, 3834636480785940480, 552187653233175429120, 106020029420769682391040, 20355845648787779019079680, 5862483546850880357494947840
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OFFSET
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1,2
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COMMENTS
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a(n) is also the determinant of the symmetric n X n matrix M defined by M(i,j) = gcd(i,j)^2 for 1 <= i,j <= n. - Avi Peretz, (njk(AT)netvision.net.il), Mar 22 2001
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REFERENCES
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L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 203, #17.
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LINKS
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FORMULA
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MAPLE
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f:= n-> LinearAlgebra:-Determinant(Matrix(n, n, (i, j) -> igcd(i, j)^2)):
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MATHEMATICA
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JordanTotient[n_, k_:1] := DivisorSum[n, #^k*MoebiusMu[n/#]&]/; (n>0)&&IntegerQ[n]; A059381[n_]:=Times@@(JordanTotient[#, 2]&/@Range[n] ); (* Enrique Pérez Herrero, Dec 29 2010 *)
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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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