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 A096842 #3 Oct 15 2013 22:32:32
%S A096842 1,3,4,7,6,8,44,222,444,888,444,888,888,2222,6666,8888,8888,222222,
%T A096842 88888,222222,444444,444444,888888,444444,444444,666666,888888,888888,
%U A096842 888888,888888,888888,444444,444444,888888,888888,888888,888888,888888
%N A096842 Sigma applied to A096841 produces these repdigits: a[n]=A000203[A096841(n)].
%e A096842 n=43:sigma[43]=44;
%t A096842 rd[x_] := Length[Union[IntegerDigits[x]]] Do[s = rd[DivisorSigma[1, n]]; s1 = DivisorSigma[1, n]; If[Equal[s, 1], Print[{n, s1}]; ta[[u]] = n; u = u + 1], {n, 1, 1000000}];ta;DivisorSigma[1, ta]
%Y A096842 Cf. A096503-A096508, A096841-A096846, A000203.
%K A096842 base,nonn
%O A096842 1,2
%A A096842 _Labos Elemer_, Jul 15 2004