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 A237815 #13 Apr 06 2014 22:21:23
%S A237815 0,0,0,0,1,2,2,3,3,4,4,4,3,3,3,3,3,2,2,3,3,3,3,2,3,5,5,5,5,5,4,4,4,4,
%T A237815 4,4,4,4,4,4,4,3,3,4,4,5,5,3,3,4,4,3,3,3,3,4,4,2,2,2,2,3,3,4,4,4,4,4,
%U A237815 4,4,4,2,2,3,3,4,4,3,3,3
%N A237815 Number of primes p < n such that the number of Sophie Germain primes among 1, ..., n-p is a Sophie Germain prime.
%C A237815 Conjecture: (i) a(n) > 0 for all n > 4.
%C A237815 (ii) For any integer n > 11, there is a prime p < n such that the number of Sophie Germain primes among 1, ..., n-p is a square.
%C A237815 See also A237817 for a similar conjecture involving twin primes.
%H A237815 Zhi-Wei Sun, <a href="/A237815/b237815.txt">Table of n, a(n) for n = 1..10000</a>
%H A237815 Z.-W. Sun, <a href="http://arxiv.org/abs/1402.6641">Problems on combinatorial properties of primes</a>, arXiv:1402.6641, 2014
%e A237815 a(5) = 1 since there are exactly two Sophie Germain primes not exceeding 5-2 = 3, and 2 is a Sophie Germain prime.
%t A237815 sg[n_]:=PrimeQ[n]&&PrimeQ[2n+1]
%t A237815 sum[n_]:=Sum[If[PrimeQ[2Prime[k]+1],1,0],{k,1,PrimePi[n]}]
%t A237815 a[n_]:=Sum[If[sg[sum[n-Prime[k]]],1,0],{k,1,PrimePi[n-1]}]
%t A237815 Table[a[n],{n,1,80}]
%Y A237815 Cf. A000040, A005384, A000290, A237705, A237706, A237768, A237817.
%K A237815 nonn
%O A237815 1,6
%A A237815 _Zhi-Wei Sun_, Feb 13 2014