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 A308091 #9 Feb 01 2021 21:18:36
%S A308091 0,0,0,0,0,0,0,0,0,0,0,6,0,0,0,12,0,12,0,0,0,0,0,24,0,0,0,0,0,30,0,72,
%T A308091 0,0,0,198,0,0,0,60,0,126,0,66,0,0,0,288,0,180,0,0,0,360,0,84,0,0,0,
%U A308091 330,0,0,0,648,0,132,0,204,0,420,0,876,0,0,0,114
%N A308091 Sum of the areas of the integer-sided triangles with perimeter n and integer area.
%H A308091 Wikipedia, <a href="https://en.wikipedia.org/wiki/Integer_triangle">Integer Triangle</a>
%F A308091 a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} m * (1 - ceiling(m) + floor(m)) * sign(floor((i+k)/(n-i-k+1))), where m = sqrt((n/2)*(n/2-i)*(n/2-k)*(i+k-n/2)).
%t A308091 Table[Sum[Sum[Sqrt[(n/2) (n/2 - i) (n/2 - k) (i + k - n/2)] (1 - Ceiling[Sqrt[(n/2) (n/2 - i) (n/2 - k) (i + k - n/2)]] + Floor[Sqrt[(n/2) (n/2 - i) (n/2 - k) (i + k - n/2)]])*Sign[Floor[(i + k)/(n - i - k + 1)]], {i, k, Floor[(n - k)/2]}], {k, Floor[n/3]}], {n, 100}]
%Y A308091 Cf. A051516.
%K A308091 nonn
%O A308091 1,12
%A A308091 _Wesley Ivan Hurt_, May 12 2019