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 A230013 #11 Feb 06 2014 18:57:03
%S A230013 2993,29993,2999993,230880803,299999993,2999999993,2999999999993
%N A230013 Numbers n such that phi(n) + sigma(n) = (3/2)*reversal(n).
%C A230013 All semiprimes of the form 3*10^m-7 are in the sequence.
%C A230013 Next term is greater than 10^8.
%t A230013 r[n_]:=FromDigits[Reverse[IntegerDigits[n]]];Do[If[c=r[n]; c>(4/3)*n && DivisorSigma[1,n] + EulerPhi[n] == (3/2)c, Print[n]], {n,100000000}]
%Y A230013 Cf. A000010, A000203, A004086, A136543.
%K A230013 nonn,base,more
%O A230013 1,1
%A A230013 _Farideh Firoozbakht_, Nov 30 2013
%E A230013 a(4)-a(7) from _Giovanni Resta_, Feb 06 2014