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 A055708 #22 Aug 15 2015 09:14:04
%S A055708 2,3,10,136,32896,2147516416
%N A055708 Numbers n such that n - 1 | sigma(n).
%C A055708 a(7) > 10^13. - _Giovanni Resta_, Jul 13 2015
%t A055708 Do[ If[ Mod[ DivisorSigma[1, n], n - 1] == 0, Print[n] ], {n, 2, 10^8} ]
%o A055708 (PARI) is(n)=sigma(n)%(n-1)==0 \\ _Anders Hellström_, Aug 15 2015
%Y A055708 Cf. A000203, A045768, A056006.
%K A055708 nonn,more
%O A055708 1,1
%A A055708 _Robert G. Wilson v_, Dec 04 2000
%E A055708 a(6) from _Donovan Johnson_, Nov 15 2009