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Search: id:A124675
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| A124675 |
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a(n) = product of the positive integers k, k<= n, such that the positive integers <= k and coprime to k are also coprime to n. |
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+0
1
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| 1, 2, 6, 8, 120, 12, 5040, 384, 324, 80, 39916800, 144, 6227020800, 672, 90, 10321920, 355687428096000, 2592, 121645100408832000, 1600, 756, 84480, 25852016738884976640000, 62208, 9000000, 1198080, 14285134080, 18816
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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The positive integers k, k <= 6, where the positive integers <= k and coprime to k are also coprime to 6, are 1,2,6. So a(6) = 1*2*6 = 12.
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MATHEMATICA
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f[n_] := Select[Range[n], GCD[ #, n] == 1 &]; g[n_] := Select[Range[n], Times @@ GCD[f[ # ], n] == 1 &]; Times @@@ Table[g[n], {n, 30}] (*Chandler*)
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CROSSREFS
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Cf. A126260, A124611.
Adjacent sequences: A124672 A124673 A124674 this_sequence A124676 A124677 A124678
Sequence in context: A007849 A100621 A002176 this_sequence A120709 A046728 A110984
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Dec 24 2006
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Dec 24 2006
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