A066574 LCM of numbers <= n and having a factor in common with n.
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
Offset: 1
Keywords
Examples
a(6) = 12 since lcm{ 1,2,3,4,6 } = 12.
Programs
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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} ]
Extensions
More terms from Robert G. Wilson v, Dec 26 2001
Comments