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 A069216 #13 Aug 29 2017 14:57:06
%S A069216 1,69,276,639,2556
%N A069216 Numbers n such that sigma(n) = reversal(n).
%C A069216 There is no further term up to 10^10. - _Farideh Firoozbakht_, Jan 20 2008
%C A069216 There is no further term up to 10^13. - _Giovanni Resta_, Jul 13 2015
%e A069216 sigma(2556) = 6552 = reversal(2556), so 2556 belongs to the sequence.
%t A069216 Do[If[DivisorSigma[1, n] == FromDigits[Reverse[IntegerDigits[n]]], Print[n]], {n, 1, 10^5}]
%t A069216 Select[Range[3000],DivisorSigma[1,#]==IntegerReverse[#]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Aug 29 2017 *)
%K A069216 base,nonn
%O A069216 1,2
%A A069216 _Joseph L. Pe_, Apr 11 2002