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 A096909 #9 Feb 16 2025 08:32:54
%S A096909 2,6,7,8,7,9,12,11,14,12,12,15,17,18,16,16,19,20,18,18,22,16,20,22,23,
%T A096909 23,25,26,21,24,24,21,22,27,30,20,25,28,28,31,32,32,26,30,30,33,27,28,
%U A096909 28,36,26,29,29,34,34,35,24,31,32,33,39,30,30,38,39,42,42,29,35,37,40
%N A096909 Primitive Pythagorean Quadruples a^2+b^2+c^2=d^2, 0<a<=b<=c<=d, gcd(a,b,c,d)=1, sorted by d, then c, then b; sequence gives c values.
%H A096909 Ivan Neretin, <a href="/A096909/b096909.txt">Table of n, a(n) for n = 1..10000</a>
%H A096909 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PythagoreanQuadruple.html">Pythagorean Quadruple.</a>
%t A096909 mx = 50; res = {}; Do[If[GCD[b, c, d] > 1, Continue[]]; If[IntegerQ[a = Sqrt[d^2 - b^2 - c^2]] && a > 0 && a <= b, AppendTo[res, {a, b, c, d}]], {d, mx}, {c, d}, {b, c}]; res[[All, 3]] (* _Ivan Neretin_, May 24 2015 *)
%Y A096909 Cf. A096907, A096908, A096910.
%K A096909 nonn,look
%O A096909 1,1
%A A096909 _Ray Chandler_, Aug 15 2004