A053568 Totients of nontotient numbers.

2, 4, 6, 6, 10, 12, 6, 8, 16, 18, 12, 22, 20, 12, 18, 28, 30, 20, 16, 24, 36, 18, 24, 40, 42, 24, 46, 42, 20, 32, 52, 40, 36, 58, 60, 30, 36, 48, 66, 32, 44, 70, 72, 36, 40, 36, 60, 78, 54, 82, 64, 42, 56, 88, 24, 72, 60, 46, 72, 96, 42, 60, 100, 102, 48, 106

Offset: 1

Author

Labos Elemer, Jan 17 2000

Keywords

• nonn

Comments

See comment at analogous sequence A053474.

Examples

			If k = 19 then there is no number x such that phi(x) = k exists; however, phi(19) = 18.
k = 27 is also a nontotient number whose totient is 18.
		

Links

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

Crossrefs

Cf. A000010, A007617, A053474.

Programs

PARI

lista(nn) = for (n=1, nn, if (!istotient(n), print1(eulerphi(n), ", "))); \\ Michel Marcus, Nov 20 2017

Formula

a(n) = A000010(A007617(n)).