Pythagorean Triples

A Pythagorean triple is a triple of integer numbers $$$(a, b, c)$$$ such that it is possible to form a right triangle with the lengths of the first cathetus, the second cathetus and the hypotenuse equal to $$$a$$$, $$$b$$$ and $$$c$$$, respectively. An example of the Pythagorean triple is $$$(3, 4, 5)$$$.

Vasya studies the properties of right triangles, and he uses a formula that determines if some triple of integers is Pythagorean. Unfortunately, he has forgotten the exact formula; he remembers only that the formula was some equation with squares. So, he came up with the following formula: $$$c = a^2 - b$$$.

Obviously, this is not the right formula to check if a triple of numbers is Pythagorean. But, to Vasya's surprise, it actually worked on the triple $$$(3, 4, 5)$$$: $$$5 = 3^2 - 4$$$, so, according to Vasya's formula, it is a Pythagorean triple.

When Vasya found the right formula (and understood that his formula is wrong), he wondered: how many are there triples of integers $$$(a, b, c)$$$ with $$$1 \le a \le b \le c \le n$$$ such that they are Pythagorean both according to his formula and the real definition? He asked you to count these triples.