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 A106499 #10 Mar 06 2020 08:11:35
%S A106499 15,28,40,45,66,77,84,91,104,120,126,144,153,170,187,190,198,209,220,
%T A106499 228,231,260,273,276,286,299,312,322,325,345,350,378,390,400,420,432,
%U A106499 435,442,459,464,476,493,496,510,522,527,544,551,558,561,570,589,608
%N A106499 Ordered perimeter of primitive integer-sided triangle one of whose angles is twice another.
%C A106499 For corresponding values of r and s, see A106500 and A106501.
%C A106499 The sides of the primitive triangle are given by the triple (r*s,s^2 - r^2,r^2).
%H A106499 Jean-François Alcover, <a href="/A106499/b106499.txt">Table of n, a(n) for n = 1..869</a>
%F A106499 a(n)=s*(r+s), where r<s<2r and (r, s)=1.
%t A106499 s[p_] := Solve[1 < r < s < 2r && p == r s + s^2 && GCD[r, s] == 1, {r, s}, Integers];
%t A106499 Reap[For[p = 1, p <= 10000, p++, sp = s[p]; If[sp =!= {}, Sow[p]; Print[p, " ", {r s, s^2 - r^2, r^2} /. sp[[1]]]]]][[2, 1]] (* _Jean-François Alcover_, Mar 06 2020 *)
%Y A106499 Cf. A106500-A106506, A106410, A106420, A106430.
%K A106499 nonn
%O A106499 1,1
%A A106499 _Lekraj Beedassy_, May 04 2005
%E A106499 Extended by _Ray Chandler_, May 09 2005