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 A306539 #23 Nov 20 2020 08:42:19
%S A306539 2,1,5,9,6,7,9,4,9,9,0,2,3,7,4
%N A306539 Decimal expansion of Sum (1/p - 1/q) as (p, q) runs through the twin primes.
%C A306539 If a = Sum (1/p) as (p, q) runs through the twin primes and
%C A306539 If b = Sum (1/q) as (p, q) runs through the twin primes, then
%C A306539 a + b = 1.902160583209... (Brun's constant) and
%C A306539 a - b = 0.215967949902374... (This constant).
%C A306539 So a = Sum_{n>=1} 1/A001359(n) = 1.059064266555685...
%C A306539 and b = Sum_{n>=1} 1/A006512(n) = 0.843096316653315... are 2 new constants for twin primes.
%F A306539 Equals 2 * A209328. - _Amiram Eldar_, Nov 20 2020
%e A306539 0.215967949902374...
%o A306539 (PARI) p=2;s=0.0;forprime(n=3,1e14,if(n-p==2,s+=(1/p-1/n));p=n;);print1(s)
%Y A306539 Cf. A065421, A001359, A006512, A001097, A209328.
%K A306539 nonn,cons,more
%O A306539 0,1
%A A306539 _Dimitris Valianatos_, Feb 22 2019