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Problem 540


Problem 540


Counting primitive Pythagorean triples

A Pythagorean triple consists of three positive integers a, b and c satsifying a2+b2=c2.
The triple is called primitive if a, b and c are relatively prime.
Let P(n) be the number of primitive Pythagorean triples with a<b<cn.
For example P(20) = 3, since there are three triples: (3,4,5), (5,12,13) and (8,15,17).

You are given that P(106) = 159139.
Find P(3141592653589793).


本原毕达哥拉斯三元组计数

毕达哥拉斯三元组包含有三个整数abc,满足等式a2+b2=c2
abc互素时,这个三元组被称为本原的。
记P(n)是满足a<b<cn本原毕达哥拉斯三元组的数目。
例如P(20) = 3,这三个三元组是:(3,4,5),(5,12,13)和(8,15,17)。

已知P(106) = 159139。
求P(3141592653589793)。


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