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Find the greatest prime divisor of the sum of the arithmetic sequence 1 + 2 + 3 + ...+ 80.

 Jun 10, 2018
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1 + 2 + 3 +........................+ 80 = 80 x 81 / 2 = 3,240

3240 = 2^3 * 3^4 * 5

5 is the greatest prime divisor.

 Jun 10, 2018

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