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 A213007 #35 May 28 2025 10:52:39
%S A213007 8,7,0,5,8,8,3,8
%N A213007 Decimal expansion of Brun's quadruple primes constant.
%C A213007 Infinite sum of the reciprocals of p, p+2, p+6, and p+8, where p ranges over all elements of A007530.
%C A213007 The 9th digit is probably 0.
%D A213007 Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 2.14, p. 133.
%H A213007 Thomas R. Nicely, <a href="https://faculty.lynchburg.edu/~nicely/quads/quads.html">Enumeration to 1.6e15 of the prime quadruplets</a>.
%H A213007 Wikipedia, <a href="http://en.wikipedia.org/wiki/Brun's_theorem">Brun's theorem</a>.
%H A213007 Wikipedia, <a href="http://en.wikipedia.org/wiki/Prime_quadruplet">Prime quadruplet</a>.
%F A213007 Sum_{n >= 1} (1/c(n) + 1/(c(n)+2) + 1/(c(n)+6) + 1/(c(n)+8)), where c(n) = A007530(n).
%e A213007 0.8705883800[+-5]
%Y A213007 Cf. A007530, A194098, A065421.
%K A213007 nonn,cons,hard,more
%O A213007 0,1
%A A213007 _Stanislav Sykora_, Jun 01 2012