A052106 a(n) = lcm(n, n - phi(n)).

0, 2, 3, 4, 5, 12, 7, 8, 9, 30, 11, 24, 13, 56, 105, 16, 17, 36, 19, 60, 63, 132, 23, 48, 25, 182, 27, 112, 29, 330, 31, 32, 429, 306, 385, 72, 37, 380, 195, 120, 41, 210, 43, 264, 315, 552, 47, 96, 49, 150, 969, 364, 53, 108, 165, 224, 399, 870, 59, 660, 61, 992, 189

Offset: 1

Author

Labos Elemer, Jan 20 2000

Keywords

• nonn

Comments

See also A009195, A003277, A050384 when totient and cototient give results identical to each other. This sequence is not identical to A009262.

a(n) = n iff n is in A246655. - Ivan Neretin, May 29 2016

Examples

			For n=255, phi(n)=128, cototient(255) = 255 - 128 = 127, a(255) = lcm(255,127) = 32385, while A009262(255) = lcm(255,phi(255)) = 128*255 = 32640;
for n=72, phi(72)=24, A051953(72) = 72 - 24 = 48, a(72) = lcm(72,48) = 144, while A009262(72) = lcm(72,24) = 72.
		

Links

• Ivan Neretin, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010, A009262, A051953.

Programs

Mathematica

Table[LCM[n, n - EulerPhi[n]], {n, 63}] (* Ivan Neretin, May 29 2016 *)

Formula

a(n) = lcm(n, A051953(n)).