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A070919
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Card{ (x,y,z) | LCM(x,y,z)=n } where LCM(x,y,z) denote the least common multiple common divisor of (x,y,z).
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4
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1, 7, 7, 19, 7, 49, 7, 37, 19, 49, 7, 133, 7, 49, 49, 61, 7, 133, 7, 133, 49, 49, 7, 259, 19, 49, 37, 133, 7, 343, 7, 91, 49, 49, 49, 361, 7, 49, 49, 259, 7, 343, 7, 133, 133, 49, 7, 427, 19, 133, 49, 133, 7, 259, 49, 259, 49, 49, 7, 931, 7, 49, 133, 127, 49, 343, 7, 133
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| A048691(n) gives Card{ (x,y) | LCM(x,y)=n }
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FORMULA
| a(n)=Sum(d|n, A000005(d)^3*A008683(n/d)); Sum(k>0, a(k)/k^s)=1/zeta(s)*Sum(k>0, tau(k)^3/k^s)
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PROG
| (PARI) for(n=1, 100, print1(sumdiv(n, d, numdiv(d)^3*moebius(n/d)), ", "))
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CROSSREFS
| Cf. A048691.
Sequence in context: A165138 A196395 A139126 * A070847 A195863 A053416
Adjacent sequences: A070916 A070917 A070918 * A070920 A070921 A070922
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KEYWORD
| mult,easy,nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), May 20 2002
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