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 A283071 #12 Mar 06 2017 02:01:13 %S A283071 3,3,0,0,9,8,0,3,5,3,9,0,0,2,2,1 %N A283071 Decimal expansion of the density of integers that are divisible by the square of their least prime factor. %F A283071 1/2^2 + (1/2)/3^2 + (1/2)*(2/3)/5^2 + (1/2)*(2/3)*(4/5)/7^2 + (1/2)*(2/3)*(4/5)*(6/7)/11^2 + .... %e A283071 0.3300980353900221... %o A283071 (PARI) primezeta(s)=my(t=s*log(2),iter=lambertw(t/eps())\t); sum(k=1,iter, moebius(k)/k*log(abs(zeta(k*s)))) %o A283071 Pz=primezeta(2); s=0; t=1.; forprime(p=2,1e10, Pz-=1/p^2; s+=t/p^2; t*=1-1/p); s+t*Pz %Y A283071 Cf. A283050. %K A283071 nonn,cons,more %O A283071 0,1 %A A283071 _Charles R Greathouse IV_ and _Michel Marcus_, Feb 28 2017