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 A239725 #13 Dec 25 2023 17:41:35 %S A239725 1,7,0,3,3,9,1,7,9,9,2,8,1,5,3,0,5,4,5,3,0,5,2,0,4,8,3,9,4,1,9,5,8,4, %T A239725 9,2,8,8,8,3,0,6,2,6,5,1,9,4,5,0,5,5,4,1,2,9,1,4,5,8,2,5,3,1,0,7,8,6, %U A239725 2,1,7,6,3,5,5,1,2,0,5,6,4,3,4,7,7,9,0 %N A239725 Decimal expansion of sum(1/k^(phi(k)), k=1..infinity), where phi(n) is the Euler totient function. %C A239725 Rational approximation: 29329/17218. %C A239725 Continued fraction: (1, 1, 2, 2, 1, 2, 4, 36, 3, 1, 11, …). %e A239725 1.70339179928153054530520483941958492888306265194505541291458253107862176... %p A239725 with(numtheory); P:=proc(q) local k; print(evalf(add(1/k^phi(k),k=1..q),100)); end: P(1000); %Y A239725 Cf. A000010, A192265, A192266. %K A239725 nonn,cons %O A239725 1,2 %A A239725 _Paolo P. Lava_, Mar 25 2014