A075857 Least common multiple of totient and cototient of n.

0, 1, 2, 2, 4, 4, 6, 4, 6, 12, 10, 8, 12, 24, 56, 8, 16, 12, 18, 24, 36, 60, 22, 16, 20, 84, 18, 48, 28, 88, 30, 16, 260, 144, 264, 24, 36, 180, 120, 48, 40, 60, 42, 120, 168, 264, 46, 32, 42, 60, 608, 168, 52, 36, 120, 96, 252, 420, 58, 176, 60, 480, 108, 32, 816, 460, 66

Offset: 1

Author

Reinhard Zumkeller, Oct 15 2002

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010, A009195, A051953.

Programs

Mathematica

Table[LCM[EulerPhi[n],(n-EulerPhi[n])],{n,70}] (* Harvey P. Dale, Jun 10 2019 *)

PARI

a(n) = {my(p = eulerphi(n)); lcm(p, n-p);} \\ Amiram Eldar, Nov 30 2024

Formula

a(n) = A000010(n)*A051953(n)/A009195(n).