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 A348143 #14 Aug 06 2024 11:28:39
%S A348143 16,18,20,30
%N A348143 Areas of integer-sided cyclic quadrilaterals whose area equals their perimeter.
%C A348143 There are no further terms. Note that without the condition "integer-sided" there are other solutions, such as (1, 17/2, 17/2, 16) which has perimeter and area 34.
%H A348143 Ralph H. Buchholz and James A. MacDougall, <a href="https://citeseerx.ist.psu.edu/pdf/56dd5d57a66e0864ff6370f7ebbb0443af9e17e2">Cyclic Polygons with Rational Sides and Area</a>, 2001. <a href="https://doi.org/10.1016/j.jnt.2007.05.005">JNT 128 (2008) 17-48</a>
%e A348143 The areas or perimeters 16, 18, 20, 30 pertain respectively to cyclic quadrilaterals with sides (4, 4, 4, 4), (3, 3, 6, 6), (2, 5, 5, 8), (5, 5, 6, 14).
%t A348143 lst={}; Do[s=(a+b+c+d)/2; If[s>a, (K=Sqrt[(s-a)(s-b)(s-c)(s-d)]; If[IntegerQ[K]&&K==2s, AppendTo[lst, Sort@{a,b,c,d}]])], {a, 1, 15}, {b, 1, a}, {c, 1, b}, {d, 1, c}]; lst
%Y A348143 Cf. A098030, A290451. First four terms of A161874.
%K A348143 fini,full,nonn
%O A348143 1,1
%A A348143 _Frank M Jackson_, Oct 02 2021