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 A209777 #12 Mar 31 2012 10:33:09 %S A209777 1,1,0,1,0,2,1,0,0,3,0,1,2,0,0,2,1,3,1,0,0,9,1,0,2,2,0,2,1,2,4,0,0,6, %T A209777 1,1,5,4,1,3,2,3,2,0,0,15,0,2,2,3,3,7,1,4,2,1,3,17,2,1,6,5,1,4,2,8,3, %U A209777 0,0,7,2,3,9,3,1,2,0,9,1,0,2,21,1,4,6,9,2,5,2,4,6,3,3,16,2,2,4,5,1,2 %N A209777 Number of q in the range 0<=q<=n for which k(n)+k(q) is prime, with k(n) := n*(n+1)^2/2. %e A209777 a(6)=2 because 147+2 and 147+50 are primes; %e A209777 a(10)=3 because 605+2, 605+224 and 605+324 are primes. %Y A209777 Cf. A006002, A130504. %K A209777 nonn %O A209777 1,6 %A A209777 _Gerasimov Sergey_, Mar 27 2012 %E A209777 Corrected by R. J. Mathar, Mar 30 2012