A072392 Numbers n such that reverse(n) = phi(n) (mod n).

21, 27, 37, 63, 270, 291, 397, 1545, 1853, 2991, 6102, 15503, 27036, 48776, 198683, 200882, 274536, 1061361, 2348128, 2723436, 2746836, 3542805, 3564217, 3868867, 3962197, 4438616, 19844683, 46676013, 69460293, 198444683, 202195682, 297828396, 309520655

Offset: 1

Author

Joseph L. Pe, Jul 21 2002

Keywords

• base
• nonn

Examples

			reverse(48776) = 67784 = 19008 (mod 48776) and 19008 = phi(48776), so 48776 is a term of the sequence.
		

Crossrefs

Cf. A000010, A103168.

Programs

Mathematica

Select[Range[10^5], Mod[ FromDigits[Reverse[IntegerDigits[n]]], # ] == EulerPhi[ # ] &]
Select[Range[45*10^5],Mod[IntegerReverse[#],#]==EulerPhi[#]&] (* The program generates the first 26 terms of the sequence. *) (* Harvey P. Dale, Feb 05 2025 *)

Extensions

More terms from Sean A. Irvine, Sep 28 2024