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 A361795 #8 Mar 24 2023 17:36:16
%S A361795 0,0,1,4,6,12,16,20,30,36,49,56,64,81,90,110,121,144,156,169,196,210,
%T A361795 240,256,272,306,324,361,380,420,441,462,506,529,576,600,625,676,702,
%U A361795 756,784,812,870,900,961,992,1056,1089,1122,1190
%N A361795 a(n) is the area of the largest rectangle with integer sides that can be drawn inside a circle of diameter n.
%C A361795 Alternatively a(n) is the area of the largest rectangle with integer sides having a diagonal of length <= n.
%C A361795 a(n) = x*x or x*(x+1) for x=floor(n/sqrt(2)).
%F A361795 a(n) = A049472(n) * A049473(n). - _Andrew Howroyd_, Mar 24 2023
%o A361795 (PARI) a(n)={my(t=sqrtint(n^2\2)); if(2*t*(t + 1) < n^2, t + 1, t)*t} \\ _Andrew Howroyd_, Mar 24 2023
%o A361795 (PARI) a(n) = sqrtint(n^2\2) * ((sqrtint(2*n^2)+1)\2) \\ _Andrew Howroyd_, Mar 24 2023
%Y A361795 Cf. A049472, A049473.
%K A361795 nonn
%O A361795 0,4
%A A361795 _John Mason_, Mar 24 2023