A354098 Numbers k such that the cototient of k (= k-phi(k)) is a multiple of 4.

1, 6, 8, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36, 38, 40, 44, 46, 48, 52, 54, 56, 60, 62, 64, 68, 72, 76, 80, 84, 86, 88, 92, 94, 96, 98, 100, 104, 108, 112, 116, 118, 120, 124, 128, 132, 134, 136, 140, 142, 144, 148, 152, 156, 158, 160, 162, 164, 166, 168, 172, 176, 180, 184, 188, 192, 196, 200, 204, 206, 208, 212

Offset: 1

Author

Antti Karttunen, May 17 2022

Keywords

• nonn

Comments

Union of {1}, A008586 \ {0, 4} and A196445 \ {2}. - Amiram Eldar, Dec 21 2023

Crossrefs

Cf. A000010, A010873, A051953, A354097 (characteristic function).

Cf. also A292763, A354038.

Cf. A008586, A196445.

Programs

Mathematica

Select[Range[200], Divisible[# - EulerPhi[#], 4] &] (* Amiram Eldar, May 17 2022 *)

PARI

A354097(n) = (0==((n-eulerphi(n))%4));
isA354098(n) = A354097(n);