Number of Pythagorean triples (a,b,c) with side a even

Use the a-slider to change its value, the i-slider will select a divisor di which must be smaller than a/2
The construction is based on the following article: E. Asmaryan, On the Generation of Pythagorean Triples and Representation of integers as a difference of two squares, Int. J. Math. Comput. Sci., 13 (2018), 59–71.