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 A115926 #15 Aug 12 2025 03:02:03
%S A115926 37,397,1853,15503,48776,198683,200882,1061361,3542805,3564217,
%T A115926 3868867,3962197,4438616,19844683,198444683,202195682,309520655,
%U A115926 431092646,439419646,500729929,535973599,3566790217,3963436297,4149753226,17296101143,39560402197
%N A115926 Numbers k such that phi(k) = reversal(k)-k.
%C A115926 All primes of the form 4*10^n-3 are in the sequence because if 4*10^n-3 is prime then phi(4*10^n-3)=(4*10^n-4) =(8*10^n-7)-(4*10^n-3)=reversal(4*10^n-3)-(4*10^n-3).
%C A115926 Also if n>1 and p=(94*10^n+113)/9 is prime then 19*p is in the sequence (the proof is easy). Next term is greater than 125*10^6.
%C A115926 If p=(1/303)*(232*10^(4n)+71) is prime then 7*p is in the sequence (the proof is easy). The first four such terms happen for n=2, 101, 104 & 444 and numbers of digits of these terms of the sequence are 9, 405, 417 & 1777 respectively. - _Farideh Firoozbakht_, Jan 02 2008
%C A115926 a(32) > 10^12. - _Giovanni Resta_, Oct 28 2012
%H A115926 Giovanni Resta, <a href="/A115926/b115926.txt">Table of n, a(n) for n = 1..31</a>
%e A115926 If n=37, phi(37) = 36 = 73-37.
%t A115926 Do[If[EulerPhi[n]==FromDigits[Reverse[IntegerDigits[n]]]-n, Print[n]], {n, 600000000}] (* Jessica M. Cornwall (jmc510(AT)psu.edu), Apr 05 2006 *)
%Y A115926 Cf. A072393.
%K A115926 nonn,base
%O A115926 1,1
%A A115926 _Farideh Firoozbakht_, Jan 31 2006
%E A115926 More terms from Jessica M. Cornwall (jmc510(AT)psu.edu), Apr 05 2006
%E A115926 a(22)-a(31) from _Giovanni Resta_, Oct 28 2012