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 A309424 #13 Aug 01 2019 11:01:58
%S A309424 3,5,5,7,7,9,7,11,9,11,13,9,11,13,15,11,13,17,11,13,17,19,13,15,17,19,
%T A309424 21,13,17,19,23,15,17,19,21,23,25,15,17,19,23,25,27,17,19,23,29,17,19,
%U A309424 21,23,25,27,29,31,19,21,23,25,27,29,31,33,19,23,25,29,31,35,21,23,25,27,29,31,33,35,37,21,23,27,29,31,33,37,39
%N A309424 Sum x+y of generator pairs (x, y) {x and y coprime and not both odd} of primitive Pythagorean triangles, sorted by x and y (for same x).
%C A309424 This sequence is based on x and y (for same x) in increasing order, directly mapping to A094192 and A094193, while A126611 is sorted by the sum x+y.
%C A309424 Given any 2 of below 4 sequences, primitive Pythagorean triangles can be generated.
%C A309424 A094192: the bigger one in generator pairs;
%C A309424 A094193: the smaller one in generator pairs;
%C A309424 A309424: the sum of generator pairs;
%C A309424 A309425: the difference of generator pairs.
%F A309424 a(n) = A094192(n) + A094193(n).
%Y A309424 Cf. A094192, A094193, A126611, A309425.
%K A309424 nonn
%O A309424 1,1
%A A309424 _Rui Lin_, Jul 31 2019