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 A335589 #15 Feb 27 2025 07:57:37
%S A335589 1,9,2,6,8,6,6,4,6,8,0,7,1,6,0,9,3,7,9,6,5,8,7,1,8,0,1,8,1,3,7,7,7,2,
%T A335589 5,5,0,4,5,7,1,8,5,5,7,9,6,6,9,0,6,0,1,5,9,9,9,1,3,9,2,9,9,0,1,8,8,4,
%U A335589 2,4,4,3,0,3,9,2,8,9,9,9,9,3,8,4,6,7,1,3,5,6,2,6,4,8,5,1,8,4,7,0,8,1,1,9,8
%N A335589 Decimal expansion of the sum of the reciprocals of the squares of composite numbers.
%F A335589 Equals Sum_{k>=1} 1/A002808(k)^2.
%F A335589 Equals A275647 - 1.
%e A335589 Equals 1/4^2 + 1/6^2 + 1/8^2 + 1/9^2 + 1/10^2 + ... = 0.19268664680716093796587180181377725504571855796690...
%t A335589 First[RealDigits[Zeta[2] - PrimeZetaP[2] - 1, 10, 100]] (* _Paolo Xausa_, Feb 27 2025 *)
%Y A335589 Cf. A002808, A275647.
%K A335589 nonn,cons
%O A335589 0,2
%A A335589 _Jon E. Schoenfield_, Jan 26 2021