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 A223941 #20 Feb 16 2025 08:33:19
%S A223941 420,55440,2042040,23931600,75698280,142334216640,1877686881840,
%T A223941 185643608470320,2137147184560080
%N A223941 Areas of primitive Heron triangles with two rational triangle medians.
%C A223941 All terms are divisible by 30.
%C A223941 It is not certain whether other values lie between those given. - _Peter Luschny_ and _Andrey Zabolotskiy_, Apr 08 2024
%H A223941 Ralph H. Buchholz and Randall L. Rathbun, <a href="http://www.jstor.org/stable/2974977">An infinite set of Heron triangles with two rational medians</a>, The American Mathematical Monthly, Vol. 104, No. 2 (Feb., 1997), pp. 107-115.
%H A223941 Andrew N. W. Hone, <a href="https://doi.org/10.1007/s00283-024-10337-2">Heron Triangles and the Hunt for Unicorns</a>, Math. Intelligencer (2024); arXiv:<a href="https://arxiv.org/abs/2401.05581">2401.05581</a> [math.NT], 2024.
%H A223941 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HeronianTriangle.html">Heronian Triangle</a>
%t A223941 (*Brute-force search*)lst = {}; Do[s = (a + b + c)/2; d = Sqrt[s*(s - a)*(s - b)*(s - c)]; If[IntegerQ[d] && Divisible[d, 30] && d > 0, p = {{a, c, b}, {b, c, a}}; t = 0; Do[m = 1/2*Sqrt[2*p[[n, 1]]^2 + 2*p[[n, 2]]^2 - p[[n, 3]]^2]; If[MatchQ[m, _Rational] || IntegerQ[m], t++, Break[]], {n, 2}]; If[t == 2, AppendTo[lst, d]]], {a, 73}, {b, 51}, {c, 26}]; lst
%Y A223941 Cf. A181928.
%Y A223941 A360537 is a subsequence.
%K A223941 hard,more,nonn
%O A223941 1,1
%A A223941 _Arkadiusz Wesolowski_, Mar 29 2013
%E A223941 a(7)-a(9) from Hone (2024) added by _Andrey Zabolotskiy_, Apr 06 2024