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A100112
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If n is the k-th squarefree number then k else 0.
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8
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1, 2, 3, 0, 4, 5, 6, 0, 0, 7, 8, 0, 9, 10, 11, 0, 12, 0, 13, 0, 14, 15, 16, 0, 0, 17, 0, 0, 18, 19, 20, 0, 21, 22, 23, 0, 24, 25, 26, 0, 27, 28, 29, 0, 0, 30, 31, 0, 0, 0, 32, 0, 33, 0, 34, 0, 35, 36, 37, 0, 38, 39, 0, 0, 40, 41, 42, 0, 43, 44, 45, 0, 46, 47, 0, 0, 48, 49, 50, 0, 0, 51, 52, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| a(A005117(n)) = n;
a(n) = (A013928(n)+1)*A008966(n).
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LINKS
| Eric Weisstein's World of Mathematics, Squarefree
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FORMULA
| a(n)=sum(k=1,n,mu(lcm(n,k))^2) - Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 14 2007
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PROG
| (PARI) a(n)=sum(k=1, n, moebius(lcm(n, k))^2) - Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 14 2007
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CROSSREFS
| Sequence in context: A132774 A007945 A011150 * A198787 A193331 A091246
Adjacent sequences: A100109 A100110 A100111 * A100113 A100114 A100115
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 07 2004
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