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 A066665 #3 Mar 30 2012 18:50:19
%S A066665 1,3,5,7,9,11,14,16,19,23,27,31,35,38,42,47,52,56,61,65,70,76,82,88,
%T A066665 94,100,107,114,121,128,136,143,150,158,166,175,185,194,203,213,223,
%U A066665 233,243,252,262,272,282,291,301,311,322,334,346
%N A066665 a(n) = #{(x,y) | 0<=y<=x<=n and x+y is prime}.
%F A066665 a(0) = 0, for n>0: a(n) = a(n-1) + A035250(n).
%e A066665 a(3)=5, as sums of (1,1), (2,0), (2,1), (3,0) and (3,2) give 5 primes.
%Y A066665 Cf. A000720, A035250.
%K A066665 nonn
%O A066665 0,2
%A A066665 _Reinhard Zumkeller_, Jan 07 2002