Using your Head is Permitted

April 2009 riddle

As a function of n, how many distinct (not congruent) integer-sided right-angle triangles are there, such that their perimeter equals 10n?

n is an integer, and the answer we are looking for is an exact closed-form formula.

List of solvers:

Dan Dima (1 April 22:35)
Mark Tilford (2 April 03:14)
Ross Millikan (2 April 05:11)
Hongcheng Zhu (2 April 20:52)
Bojan Bašić (5 April 06:17)
Sen Gu (10 April 13:54)
Slobodan Mitrović (14 April 03:01)
Aleksandar Ilic (14 April 04:11)
Itsik Horovitz (30 April 22:22)

Elegant solutions can be submitted to the puzzlemaster at Names of solvers will be posted on this page. Notify if you don't want your name to be mentioned.

The solution will be published at the end of the month.


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