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 A239246 #21 Feb 16 2025 08:33:21
%S A239246 0,0,0,0,1,1,0,1,0,0,0,0,2,0,2,0,3,0,0,2,2,0,0,1,3,2,0,1,2,3,0,0,0,0,
%T A239246 2,1,5,0,4,3,4,1,0,2,1,0,0,2,0,2,4,6,4,0,2,2,0,2,0,1,3,0,1,0,8,2,0,5,
%U A239246 1,2,0,0,6,2,7,0,3,0,0,3,0,2,0,0,9
%N A239246 Number of primitive Heronian triangles with n as greatest side length.
%H A239246 Giovanni Resta, <a href="/A239246/b239246.txt">Table of n, a(n) for n = 1..10000</a>
%H A239246 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HeronianTriangle.html">Heronian Triangle.</a>
%e A239246 a(17)=3 as there are 3 primitive Heronian triangles with greatest side length of 17. They are (9, 10, 17), (8, 15, 17) and (16, 17, 17).
%t A239246 nn=200; lst={}; Do[s=(a+b+c)/2; If[IntegerQ[s]&&GCD[a, b, c]==1, area2=s(s-a)(s-b)(s-c); If[area2>0&&IntegerQ[Sqrt[area2]], AppendTo[lst, c]]], {c, 3, nn}, {b, c}, {a, b}]; Table[Length@Select[lst, #==n &], {n, 1, nn}] (* using _T. D. Noe_'s program at A083875 *)
%Y A239246 Cf. A054875, A070138, A096467, A123323, A134587.
%K A239246 nonn
%O A239246 1,13
%A A239246 _Frank M Jackson_, Mar 13 2014