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 A307109 #9 Mar 26 2019 08:27:37 %S A307109 1,1,4,5,5,5,11,11,12,12,12,15,21,21,21,22,22,22,28,28,34,34,34,34,35, %T A307109 35,38,44,44,44,50,50,50,50,50,51,57,57,63,63,63,63,69,69,69,69,69,72, %U A307109 79,79,79,85,85,85,85,85,91,91,91,91,97,97,103,104,104,104 %N A307109 Number of integer solutions to x^2 + x*y + y^2 <= n excluding (0,0), divided by 2. %e A307109 a(1)=a(2)=(2/2)=1: 2 solutions (-1,1),(1,-1); %e A307109 a(3)=(8/2)=4: 2 solutions for n<3 and the 6 solutions (1,1), (-1,-1), (1,-2), (2,-1), (-1,2), (-2,1); %e A307109 a(4)=a(5)=a(6)=10/2=5: 8 solutions for n<6 and the 2 solutions (-2,2), (2,-2). %Y A307109 Cf. A014201, A014202, A198799, A230655, A300419. %K A307109 nonn %O A307109 1,3 %A A307109 _Hugo Pfoertner_, Mar 25 2019