A primitive Pythagorean triple is a Pythagorean triple
such that
,
where
is the greatest common divisor. A right
triangle whose side lengths give a primitive Pythagorean triple is then known
as a primitive right triangle.
Lehmer (1900) showed that the fraction of primitive triples with perimeter less than
is
(1)
| |||
(2)
|
(OEIS A118858).