A063742 Cototients: numbers k such that x - phi(x) = k has at least one solution.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 53, 54, 55, 56, 57, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78

Offset: 1

Author

Labos Elemer, Aug 13 2001, corrected May 20 2003

Keywords

• nonn

Comments

Numbers in range of A051953, the cototients. Complement of non-cototients, A005278 with respect to natural numbers A000027.

Examples

			First missing numbers are: 10,26,34,50,52,... These missing values are collected in A005278.
		

Links

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

Crossrefs

Cf. A000010, A005278, A051953, A083533, A083534, A083536.

Analogous to A002202.

Programs

Mathematica

Union[Table[w-EulerPhi[w], {w, 1, A}]] (* taken for sufficiently large A. *)

Extensions

Edited by N. J. A. Sloane, Nov 17 2008 at the suggestion of R. J. Mathar