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 A074236 #19 Jan 29 2024 19:12:33
%S A074236 15,20,30,35,40,45,52,55,60,68,70,75,80,90,91,100,104,105,110,116,117,
%T A074236 120,135,136,140,143,148,150,153,156,160,164,165,175,180,182,187,195,
%U A074236 200,204,208,210,212,220,221,225,232,234,240,244,245,247,255,260,270
%N A074236 Numbers that are the long leg of some integer right triangle and the hypotenuse of some other integer right triangle.
%C A074236 A009003 gives ordered values of hypotenuses of integer right triangles; A009012 gives ordered values of long legs of integer right triangles. Their intersection is this sequence.
%C A074236 Note that all terms are composite.
%F A074236 Intersection of A009012 and A009003.
%e A074236 15 is a term because it is the long leg of the integer right triangle with sides 8, 15, 17 and the hypotenuse of the integer right triangle with sides 9, 12, 15.
%t A074236 prims=With[{cps=Select[Subsets[Range[1,221,2],{2}],CoprimeQ@@#&]}, ptrip[ {a_,b_}]:={a*b,(b^2-a^2)/2,(b^2+a^2)/2};Sort[Sort/@(ptrip/@cps)]]; pyths= Sort[Flatten[Table[n #&/@prims,{n,200}],1]]; Take[Intersection[ Transpose[ pyths][[2]],Transpose[pyths][[3]]],80] (* _Harvey P. Dale_, Apr 26 2012 *)
%Y A074236 Cf. A009003, A009012.
%K A074236 nonn
%O A074236 1,1
%A A074236 _Zak Seidov_, Sep 18 2002
%E A074236 Corrected by _Harvey P. Dale_, Apr 26 2012