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 A074242 #15 Jun 26 2015 04:47:51
%S A074242 5602,42346,184650339,356930335,453038125082
%N A074242 Numbers n such that sigma(n+1) = reverse(sigma(n)).
%C A074242 a(6) > 10^13. - _Giovanni Resta_, Jun 26 2015
%e A074242 sigma(5602 + 1) = 6048 = reverse(8406) = reverse(sigma(5602)), so 5602 is a term of the sequence.
%t A074242 Do[ If[FromDigits[Reverse[IntegerDigits[DivisorSigma[1, n]]]] == DivisorSigma[1, n + 1], Print[n]], {n, 1, 10^7}]
%o A074242 (PARI) isok(n) = digits(sigma(n+1)) == Vecrev(digits(sigma(n))); \\ _Michel Marcus_, Jun 26 2015
%Y A074242 Cf. A028980 (sigma(n) = reverse(sigma(n))).
%K A074242 base,more,nonn
%O A074242 1,1
%A A074242 _Joseph L. Pe_, Sep 19 2002
%E A074242 a(3)-a(4) from _Donovan Johnson_, Feb 01 2009
%E A074242 a(5) from _Giovanni Resta_, Jun 26 2015