This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A072392 #15 Feb 05 2025 18:09:25 %S A072392 21,27,37,63,270,291,397,1545,1853,2991,6102,15503,27036,48776,198683, %T A072392 200882,274536,1061361,2348128,2723436,2746836,3542805,3564217, %U A072392 3868867,3962197,4438616,19844683,46676013,69460293,198444683,202195682,297828396,309520655 %N A072392 Numbers n such that reverse(n) = phi(n) (mod n). %e A072392 reverse(48776) = 67784 = 19008 (mod 48776) and 19008 = phi(48776), so 48776 is a term of the sequence. %t A072392 Select[Range[10^5], Mod[ FromDigits[Reverse[IntegerDigits[n]]], # ] == EulerPhi[ # ] &] %t A072392 Select[Range[45*10^5],Mod[IntegerReverse[#],#]==EulerPhi[#]&] (* The program generates the first 26 terms of the sequence. *) (* _Harvey P. Dale_, Feb 05 2025 *) %Y A072392 Cf. A000010, A103168. %K A072392 base,nonn %O A072392 1,1 %A A072392 _Joseph L. Pe_, Jul 21 2002 %E A072392 More terms from _Sean A. Irvine_, Sep 28 2024