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Search: id:A060654
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| 1, 1, 2, 1, 3, 1, 4, 3, 5, 1, 6, 1, 7, 5, 8, 1, 9, 1, 10, 7, 11, 1, 12, 5, 13, 9, 14, 1, 30, 1, 16, 11, 17, 7, 18, 1, 19, 13, 20, 1, 21, 1, 22, 15, 23, 1, 24, 7, 25, 17, 26, 1, 27, 11, 28, 19, 29, 1, 60, 1, 31, 21, 32, 13, 33, 1, 34, 23, 70, 1, 36, 1, 37, 25, 38, 11, 39, 1, 40, 27, 41
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OFFSET
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0,3
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FORMULA
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a(n)=GCD[n, Apply[LCM, dd[n]]], where dd[n] is the first difference of divisors (ordered by size).
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EXAMPLE
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If n is prime p, then A060766(p)=p-1 and LCM[p, p-1]=1. If n=2k then a(2k)=k or as an "anomaly", a(2k)=2k n=30, D={1, 2, 3, 5, 6, 10, 15, 30}, dD={1, 1, 2, 1, 4, 5, 15}={1, 2, 4, 5, 15}, LCM[dD]=60, GCD[n, LCM[dD[n]]]=GCD[30, 60]=30=n n=36 D={1, 2, 3, 4, 6, 9, 12, 18, 36}, dD={1, 1, 1, 2, 3, 3, 6, 18}={1, 2, 3, 6, 18}, LCM[dD]=18, GCD[n, LCM[dD[n]]]=GCD[36, 18]=18=n/2
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CROSSREFS
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Cf. A060680-A060685, A060741, A060742, A060763-A060766, A000005.
Sequence in context: A079880 A159353 A032742 this_sequence A116512 A075388 A036445
Adjacent sequences: A060651 A060652 A060653 this_sequence A060655 A060656 A060657
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Apr 25 2001
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