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 A342201 #13 Mar 08 2021 08:48:23
%S A342201 2,0,4,9,3,2,5,9,1,4,6,2,4,9,5,7,1,9,3,5,1,3,7,4,6,4,3,3,5,3,5,7,0,1,
%T A342201 5,3,1,0,1,6,3,8,7,7,1,1,9,0,2,1,7,8,8,6,2,5,4,9,8,7,1,9,6,9,5,4,7,2,
%U A342201 4,0,4,2,4,6,5,4,2,1,3,3,4,9,7,6,1,6,0,6,0,5,1,2,3,4,2,0,0,5,5,1,8,8,9,9
%N A342201 Decimal expansion of Sum_{k>=1} (1 - (1/k)^(1/k^k)).
%e A342201 0.204932591462...
%o A342201 (PARI) suminf(k=1, 1 - (1/k)^(1/k^k)) \\ _Michel Marcus_, Mar 05 2021
%Y A342201 Cf. A342200.
%K A342201 nonn,cons
%O A342201 0,1
%A A342201 _Koksal Karakus_, Mar 04 2021
%E A342201 More digits from _Alois P. Heinz_, Mar 05 2021