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 A375474 #13 Aug 17 2024 22:43:08
%S A375474 3,7,10,11,12,14,15,17,19,23,26,27,28,30,31,35,39,40,42,43,44,46,47,
%T A375474 48,51,55,56,58,59,60,62,63,67,68,69,71,74,75,76,77,78,79,82,83,87,90,
%U A375474 91,92,94,95,97,99,103,104,105,106,107,108,110,111,112,113,115,119,120,122,123
%N A375474 Numbers k such that k is the area of a rational isosceles triangle.
%C A375474 All the integer areas of rational isosceles triangles can be obtained by multiplying a squarefree area of a rational isosceles triangle A375017 by a positive square number A000290.
%H A375474 Frank M Jackson, <a href="/A375474/b375474.txt">Table of n, a(n) for n = 1..2895</a>
%e A375474 12 is the area of an isosceles triangle with sides (5, 5, 6).
%e A375474 40 is the area of an isosceles triangle with sides (12, 82/3, 82/3).
%t A375474 lst=Last/@ReadList["https://oeis.org/A375017/b375017.txt", {Number, Number}]; dmax=75; Select[(Sort@Flatten@Table[Table[lst[[n]]*d^2, {d, 1, dmax}], {n, 1, Length@lst}]), #<=140 &]
%Y A375474 Cf. A000290, A375017.
%K A375474 nonn
%O A375474 1,1
%A A375474 _Frank M Jackson_, Aug 17 2024