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$60$-degree Triangle Inscribed Circles

  Published on Friday, 23rd May 2008, 02:00 pm and solved by 2059
Difficulty: Level 16 [41%]

Problem 195

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

Find $T(1053779)$.



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