perplexus.info :: Just Math : Squares sum up to a prime

Squares sum up to a prime (Posted on 2017-01-13)

List all integers n such that the sum 2^2 + 3^2 + 4^2 + ... + n^2 equals a prime number. p&p solutions only.

See The Solution Submitted by Ady TZIDON

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re: solution

| Comment 3 of 6 |

(In reply to solution by xdog)

(n-1)*(2n^2 +5n + 6)/6.

should be presented as

(n-1)/6 * (2n^2 +5n + 6)

to be coherent with defining (n-1)/6 as the 1st factor

Posted by Ady TZIDON on 2017-01-13 22:24:02

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