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 A106410 #11 Mar 07 2020 05:07:42 %S A106410 4,9,9,16,25,16,25,36,25,49,25,49,64,49,36,81,49,64,81,49,100,49,64, %T A106410 121,81,100,121,81,144,64,121,169,121,81,169,121,196,81,100,169,121, %U A106410 144,225,169,121,196,225,100,169,256,121,144,169,121,196,289,225,169,256,121 %N A106410 Length of side opposite the lesser of the two angles, one being the double of the other, of a primitive integer-sided triangle, sorted on perimeter(A106499). %F A106410 a(n) = A106500(n)^2. %t A106410 sol[p_] := Solve[1 < r < s < 2 r && p == r s + s^2 && GCD[r, s] == 1, {r, s}, Integers]; %t A106410 Reap[For[p = 1, p <= 1000, p++, sp = sol[p]; If[sp =!= {}, Print[r^2 /. sp[[1]]]; Sow[r^2 /. sp[[1]]]]]][[2, 1]] (* _Jean-François Alcover_, Mar 07 2020 *) %Y A106410 Cf. A106499-A106506, A106420, A106430. %K A106410 nonn %O A106410 1,1 %A A106410 _Lekraj Beedassy_ and _Ray Chandler_, May 09 2005