A124443 a(1)=1, a(n) = LCM of the integers, from 1 to n/2, which are coprime to n.

1, 1, 1, 1, 2, 1, 6, 3, 4, 3, 60, 5, 60, 15, 28, 105, 840, 35, 2520, 63, 40, 315, 27720, 385, 5544, 3465, 40040, 6435, 360360, 1001, 360360, 45045, 7280, 45045, 350064, 85085, 12252240, 765765, 1989680, 2909907, 232792560, 230945, 232792560, 1322685

Offset

1,5

Links

Table of n, a(n) for n=1..44.

Example

The integers which are >= 1 and are <= 9/2 and which are coprime to 9 are 1, 2 and 4. So a(9) = lcm(1,2,4) = 4.

Mathematica

f[n_] := If[n == 1, 1, LCM @@ Select[Range[Floor[n/2]], GCD[ #, n] == 1 &]]; Table[f[n], {n, 45}] (* Ray Chandler, Nov 12 2006 *)

Prog

(PARI) a(n) = lcm(select(x->(gcd(x, n)==1), vector(n\2, k, k))); \\ Michel Marcus, Mar 18 2018

Crossrefs

Cf. A124444.

Sequence in context: A289869 A334595 A350684 * A077172 A160047 A249990

Adjacent sequences: A124440 A124441 A124442 * A124444 A124445 A124446

Keyword

nonn

Author

Leroy Quet, Nov 01 2006

Extensions

Extended by Ray Chandler, Nov 12 2006

Status

approved