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 A108393 #3 Mar 31 2012 20:08:02 %S A108393 1,1,1,1,1,1,1,1,0,2,2,2,1,1,2,1,2,1,1,1,2,2,0,1,2,1,3,2,2,0,3,1,3,2, %T A108393 1,3,2,5,2,2,5,2,2,3,3,1,3,2,4,3,1,1,2,1,3,4,2,2,4,1,3,2,4,3 %N A108393 a(n)=number of primes of the form p^2+k^2 with 2<=k<=floor(sqrt(2*p+1)) (less than (p+1)^2), for every p(n). %C A108393 Conjecture: 23,83,113 and 811 are the only primes with a 0 value in the sequence. There is always a prime of the form p^2+k^2 (1 mod 4) between p^2 and (p+1)^2 for every prime not 23,83,113 or 811. %e A108393 a(5)=1 because p(5)=11 and very is only one value of k<=floor(sqrt(2*11+1))=4 for which p(5)^2+k^2 is prime: 11^2+4^2=137 %e A108393 a(27)=3 because p(27)=103 and 103^2+2^2=10613,103^2+10^2=10709,103^2+12^2=10753 are primes. %Y A108393 Cf. A108714. %K A108393 nonn %O A108393 1,10 %A A108393 _Robin Garcia_, Jul 02 2005