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 A215140 #11 Apr 20 2018 11:49:05
%S A215140 1,1,2,7,2,8,2,0,1,7,2,8,3,2,6,5,8,9,0,3,4,4,3,7,9,7,2,3,2,7,2,5,0,6,
%T A215140 1,3,5,6,6,1,4,1,2,3,0,9,9,8,4,9,3,1,2,2,4,5,4,0,9,6,5,5,6,2,7,3,8,6,
%U A215140 4,3,1,9,5,1,8,1,5,2,5,9,6,7,0,6,3,4,9
%N A215140 Decimal expansion of Sum_{n>=1} 1 / sigma(n)^n.
%H A215140 G. C. Greubel, <a href="/A215140/b215140.txt">Table of n, a(n) for n = 1..5000</a>
%e A215140 1.127282017283265890344379...
%t A215140 RealDigits[N[Sum[1/DivisorSigma[1,n]^n,{n,1,105}],105]][[1]]
%o A215140 (PARI) suminf(n=1, 1/sigma(n)^n) \\ _Michel Marcus_, Apr 20 2018
%Y A215140 Cf. A000203.
%K A215140 nonn,cons
%O A215140 1,3
%A A215140 _Michel Lagneau_, Aug 04 2012