A117638 Numbers k for which the digital root of phi(k) divides k.

1, 2, 4, 6, 8, 11, 12, 16, 18, 21, 22, 24, 27, 29, 36, 42, 44, 47, 50, 54, 58, 63, 66, 72, 78, 80, 81, 83, 84, 85, 88, 90, 94, 100, 101, 105, 108, 116, 117, 120, 125, 126, 128, 129, 132, 135, 136, 137, 144, 147, 156, 160, 162, 166, 168, 170, 171, 173, 174, 176, 180

Offset

1,2

Links

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

Example

105 is in the sequence because phi(105) = 48 and the digital root of 48 (3) divides 105.

Mathematica

Select[Range[180], Divisible[#, Mod[EulerPhi[#] - 1, 9] + 1] &] (* Amiram Eldar, Feb 06 2021 *)

Crossrefs

Cf. A000010, A010888.

Sequence in context: A187348 A081499 A342527 * A128403 A205556 A051244

Adjacent sequences: A117635 A117636 A117637 * A117639 A117640 A117641

Keyword

nonn,base

Author

Luc Stevens (lms022(AT)yahoo.com), Apr 09 2006

Extensions

Offset corrected by Amiram Eldar, Feb 06 2021

Status

approved