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A066574
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LCM of numbers <= n and having a factor in common with n.
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2
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1, 2, 3, 4, 5, 12, 7, 24, 18, 120, 11, 360, 13, 840, 180, 1680, 17, 5040, 19, 5040, 1260, 55440, 23, 55440, 300, 720720, 7560, 720720, 29, 10810800, 31, 1441440, 83160, 24504480, 2100, 73513440, 37, 465585120, 1081080, 2327925600, 41, 1396755360
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| If n is not composite then a(n) = n.
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EXAMPLE
| a(6) = 12 since lcm{ 1,2,3,4,6 } = 12.
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MAPLE
| A066574 := n -> ilcm(op(select(k->igcd(n, k)<>1, [$1..n]))); seq(A066574(i), i=1..42); # Peter Luschny, Jun 25 2011
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MATHEMATICA
| f[n_] := Block[{a = 1, k = 2}, While[k < n + 1, If[ GCD[k, n] > 1, a = LCM[a, k]]; k++ ]; Return[a]]; Table[ f[n], {n, 1, 45} ]
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CROSSREFS
| Sequence in context: A064446 A143482 A193679 * A039007 A050745 A077375
Adjacent sequences: A066571 A066572 A066573 * A066575 A066576 A066577
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KEYWORD
| nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Dec 19 2001
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 26 2001
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