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 A120961 #16 Nov 28 2019 13:54:57
%S A120961 25,65,85,125,145,169,185,205,221,265,289,305,325,365,377,425,445,481,
%T A120961 485,493,505,533,545,565,625,629,685,689,697,725,745,785,793,841,845,
%U A120961 865,901,905,925,949,965,985,1025,1037,1073,1105,1145,1157,1165,1189,1205
%N A120961 Composite hypotenuses of primitive Pythagorean triangles.
%C A120961 Composite entries of A008846. Disjoint union of A024409 and A146945.
%H A120961 Ray Chandler, <a href="/A120961/b120961.txt">Table of n, a(n) for n = 1..10000</a>
%H A120961 César Aguilera, <a href="https://hal.archives-ouvertes.fr/hal-02151737">On Pythagorean Triples</a>, hal-02151737 preprint [math.NT], 2019.
%t A120961 lst = {}; Do[ If[ GCD[m, n] == 1, a = 2 m*n; b = m^2 - n^2; c = m^2 + n^2; If[ !PrimeQ@c, AppendTo[lst, c]]], {m, 3, 300}, {n, If[ OddQ@m, 2, 1], m - 1, 2}]; Take[ Union@ lst, 51] (* _Robert G. Wilson v_, May 02 2009 *)
%Y A120961 Cf. A120960, A008846, A146945, A024409.
%K A120961 nonn
%O A120961 1,1
%A A120961 _Lekraj Beedassy_, Jul 19 2006
%E A120961 Term 485, which satisfies 485^2 = 476^2 + 93^2, added by _Robert G. Wilson v_, May 02 2009