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 A072294 #31 Nov 14 2019 15:40:13
%S A072294 6,12,12,30,60,24,84,36,60,120,66,42,84,126,60,90,84,168,36,204,210,
%T A072294 210,60,120,132,72,84,252,360,114,156,180,210,420,120,210,420,168,420,
%U A072294 240,468,126,180,336,360,420,264,330,252,168,504,420,780,420,306,456,156
%N A072294 Areas of primitive Heronian triangles sorted by longest side, then by middle side and finally shortest side.
%H A072294 Ray Chandler, <a href="/A072294/b072294.txt">Table of n, a(n) for n = 1..10000</a> (first 2197 terms from Zak Seidov)
%H A072294 A. Dendane, <a href="http://www.analyzemath.com/Geometry_calculators/herons_area_triangle.html">Heron's Formula for Area of a Triangle-Geometry Calculator</a>
%H A072294 Zak Seidov, <a href="/A072294/a072294_1.txt">Table of n=1..6093, A072294(n), A120131(n), A120132(n), A120133(n)</a> (with A120131(n) <=1000)
%H A072294 Michael Somos, <a href="http://grail.eecs.csuohio.edu/~somos/tritab.html">Heronian Triangle Table</a>
%H A072294 P. Yiu, <a href="http://math.fau.edu/yiu/RecreationalMathematics2003.pdf">Heron triangles with sides < 100</a> Appendix Chap. 9.3 pp. 81/360 in 'Recreational Mathematics'.
%t A072294 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, Sqrt[area2]]]], {a, nn}, {b, a}, {c, b}]; lst (* _T. D. Noe_, Mar 23 2011 *)
%Y A072294 Cf. A120131, A120132, A120133, A055595.
%K A072294 nonn
%O A072294 1,1
%A A072294 _Lekraj Beedassy_, Jul 12 2002
%E A072294 More terms from _Ray Chandler_, Jul 02 2004