A309425 - OEIS

%I #8 Aug 02 2019 23:05:05

%S 1,1,3,1,3,1,5,1,5,3,1,7,5,3,1,7,5,1,9,7,3,1,9,7,5,3,1,11,7,5,1,11,9,

%T 7,5,3,1,13,11,9,5,3,1,13,11,7,1,15,13,11,9,7,5,3,1,15,13,11,9,7,5,3,

%U 1,17,13,11,7,5,1,17,15,13,11,9,7,5,3,1,19,17,13,11,9,7,3,1

%N Difference x-y of generator pairs (x,y) {x and y coprime and not both odd, x > y} of primitive Pythagorean triangles, sorted by x and y (for same x).

%C This sequence is based on x and y (for same x) in increasing order, directly mapping to A094192 and A094193, while A126637 is sorted by the sum x+y.

%C Given any two of the four sequences below, primitive Pythagorean triangles can be generated.

%C A094192: the bigger one in generator pairs;

%C A094193: the smaller one in generator pairs;

%C A309424: the sum of generator pairs;

%C A309425: the difference of generator pairs.

%F a(n) = A094192(n) - A094193(n).

%Y Cf. A094192, A094193, A126637, A309424.

%K nonn

%O 1,3

%A _Rui Lin_, Jul 31 2019