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 A295820 #26 Jul 05 2018 09:10:46
%S A295820 0,2,3,3,3,5,5,5,5,5,7,7,7,9,9,9,9,11,11,11,11,11,11,11,11,13,15,15,
%T A295820 15,17,17,17,17,17,19,19,19,21,21,21,21,23,23,23,23,23,23,23,23,23,25,
%U A295820 25,25,27,27,27,27,27,29,29,29,31,31,31,31,35,35,35,35,35,35
%N A295820 Number of nonnegative solutions to (x,y) = 1 and x^2 + y^2 <= n.
%H A295820 Seiichi Manyama, <a href="/A295820/b295820.txt">Table of n, a(n) for n = 0..1000</a>
%F A295820 a(n) = a(n-1) + A295819(n) for n > 0.
%e A295820 Solutions to (x,y) = 1 and x^2 + y^2 <= 17;
%e A295820 * (1,4)
%e A295820 * * (1,3), (2,3)
%e A295820 * * (1,2), (3,2)
%e A295820 * * * * * (0,1), (1,1), (2,1), (3,1), (4,1)
%e A295820 * (1,0)
%e A295820 a(17) = 11.
%t A295820 a[n_] := Sum[Boole[GCD[i, j]==1 ], {i, 0, Sqrt[n]}, {j, 0, Sqrt[n-i^2]}];
%t A295820 Table[a[n], {n, 0, 100}] (* _Jean-François Alcover_, Jul 05 2018, after _Andrew Howroyd_ *)
%o A295820 (PARI) a(n) = {sum(i=0, sqrtint(n), sum(j=0, sqrtint(n-i^2), gcd(i, j) == 1))} \\ _Andrew Howroyd_, Dec 12 2017
%Y A295820 Cf. A049643, A224212, A295819, A295849.
%K A295820 nonn
%O A295820 0,2
%A A295820 _Seiichi Manyama_, Nov 28 2017