A049225 Values of totient function applied to squarefree numbers; or numbers of form Product (p_i-1) where p_i are distinct primes.

1, 2, 4, 6, 8, 10, 12, 16, 18, 20, 22, 24, 28, 30, 32, 36, 40, 42, 44, 46, 48, 52, 56, 58, 60, 64, 66, 70, 72, 78, 80, 82, 84, 88, 92, 96, 100, 102, 104, 106, 108, 112, 116, 120, 126, 128, 130, 132, 136, 138, 140, 144, 148, 150, 156, 160, 162, 164, 166, 168, 172, 176

Offset: 1

Author

Labos Elemer

Keywords

• nonn

Comments

Numbers m such that m = phi(k) and |mu(k)| = 1.

Examples

			8, 120, 48 are terms as totients of the squarefree numbers 15, 143, 210.
54, 110 are not terms since there are no squarefree numbers k such that phi(k) = 54, 110.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems (invphi.gp).

Crossrefs

Terms of A049200 after ordering and omitting multiple occurrences.

Cf. A000010, A005117, A008683, A013929, A002174, A002202, A049200.

Programs

PARI

isok(n) = {my(v = invphi(n)); (#v) && (#select(x->issquarefree(x), v));} \\ Michel Marcus, Feb 25 2019