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Problem 195


Problem 195


Inscribed circles of triangles with one angle of 60 degrees

Let’s call an integer sided triangle with exactly one angle of 60 degrees a 60-degree triangle.
Let r be the radius of the inscribed circle of such a 60-degree triangle.

There are 1234 60-degree triangles for which r ≤ 100.
Let T(n) be the number of 60-degree triangles for which r ≤ n, so
T(100) = 1234,  T(1000) = 22767, and  T(10000) = 359912.

Find T(1053779).


有一角为60度的三角形的内切圆

我们称恰好有一个角为60度的整数边长三角形为60度三角形。
记r是这个60度三角形的内切圆的半径。

当r ≤ 100时,一共有1234个60度三角形。
记T(n)是r ≤ n时所有的60度三角形数目,因此
T(100) = 1234,  T(1000) = 22767,以及  T(10000) = 359912.

求T(1053779)。