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A059381
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Product J_2(i), i=1..n (cf. A007434).
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6
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1, 3, 24, 288, 6912, 165888, 7962624, 382205952, 27518828544, 1981355655168, 237762678620160, 22825217147535360, 3834636480785940480, 552187653233175429120, 106020029420769682391040, 20355845648787779019079680, 5862483546850880357494947840
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| 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
| L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 203, #17.
Antal Bege, Hadamard product of GCD matrices, Acta Univ. Sapientiae, Mathematica, 1, 1 (2009) 43-49
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FORMULA
| a(n)=A001088(n)*A175836(n) - Enrique Pérez Herrero, Oct 08 2011.
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MATHEMATICA
| JordanTotient[n_, k_:1] := DivisorSum[n, #^k*MoebiusMu[n/#]&]/; (n>0)&&IntegerQ[n]; A059381[n_] := Times@@(JordanTotient[#, 2]&/@Range[n]) (* From Enrique Pérez Herrero, Dec 29 2010 *)
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CROSSREFS
| Cf. A001088, A175836
Sequence in context: A064037 A128572 A052592 * A138209 A075142 A138428
Adjacent sequences: A059378 A059379 A059380 * A059382 A059383 A059384
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Jan 28 2001
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