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 A362669 #31 Feb 16 2025 08:34:05
%S A362669 10,20,21,24,30,36,40,42,48,50,55,60,63,70,72,78,80,84,90,96,100,105,
%T A362669 108,110,112,120,126,130,136,140,144,147,150,156,160,165,168,170,171,
%U A362669 180,189,190,192,195,200,210,216,220,224,230,231,234,240,250,252,253,260,264,270,272,273,275
%N A362669 Integer inradii for which there exists an isosceles triangle with integer sides (a, b, b) where a < b.
%C A362669 The inradius for isosceles triangle (a, b, b) is r = (a/2)*sqrt((2*b-a)/(2*b+a)).
%C A362669 If m is a term, so is k*m with k > 1; hence, A008592 \ {0} is a subsequence.
%H A362669 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Incircle.html">Incircle</a>.
%H A362669 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IsoscelesTriangle.html">Isosceles Triangle</a>.
%e A362669 The smallest inradius, r = 10, corresponds to isosceles triangle (30, 39, 39).
%e A362669 The third inradius, r = 21, corresponds to isosceles triangle (56, 100, 100).
%e A362669 r = 60 is the first inradius for which there exist two such isosceles triangles: (168, 259, 259) and (180, 234, 234).
%t A362669 Select[Range[300], Length @ Reduce[#^2 == a^2*(2*b - a)/(4*(2*b + a)) && 0 < a < b, {a, b}, Integers] > 0 &] (* _Amiram Eldar_, May 05 2023 *)
%Y A362669 Cf. A008592, A070204, A120062, A120570, A362670 (similar but with (a,a,c)).
%K A362669 nonn
%O A362669 1,1
%A A362669 _Bernard Schott_, Apr 29 2023