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 A230012 #18 Feb 05 2014 10:37:18
%S A230012 19,199,437,603,1999,12834,16348,21293,22183,23383,25273,27263,44377,
%T A230012 46367,199999,670661,691351,803851,845321,1425650,2103643,2111191,
%U A230012 2123893,2174143,2543773,2552723,2753713,3791659,4003997,4034347,4133332,4223887,4244287,4492429,4663667
%N A230012 Numbers n such that phi(n) = sigma(n) - reversal(sigma(n)).
%C A230012 A prime p is in the sequence iff p is of the form 2*10^m-1. 19, 199, 1999 are such terms of the sequence.
%C A230012 If both numbers p=2*10^m-1 and q=2*10^m+3 are prime then n=p*q is in the sequence. For m=1, 3, 5, 7 both p and q are prime.
%C A230012 If both numbers p=2*10^m-1 and q=(7*10^m-1)/3 are prime then n=p*q is in the sequence. For m=1, 2, 3, 53 both p and q are prime.
%H A230012 Giovanni Resta, <a href="/A230012/b230012.txt">Table of n, a(n) for n = 1..103</a> (terms < 10^11)
%t A230012 r[n_]:=FromDigits[Reverse[IntegerDigits[n]]];Do[If[DivisorSigma[1,n]- r[DivisorSigma[1,n]]==EulerPhi[n],Print[n]],{n,15000000}]
%Y A230012 Cf. A000010, A000203, A004086, A069225, A237257.
%K A230012 base,nonn
%O A230012 1,1
%A A230012 _Farideh Firoozbakht_, Feb 04 2014