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Sum of primes is a square (Posted on 2012-06-29) Difficulty: 3 of 5
Let's define S(k) = p1 + p2 + ... + pk, i.e. "the sum of the first k primes"
The sum of the first 9 consecutive prime numbers equals 100, a square number.

Find all k (below 9999) that will similarly produce perfect squares.

See The Solution Submitted by Ady TZIDON    
Rating: 5.0000 (1 votes)

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Solution re: computer solution with an extension Comment 2 of 2 |
(In reply to computer solution with an extension by Charlie)

A search in Sloane's OEIS, finds 9, 2474, 6694, 7785, 709838, 126789311423, (series A033997 ), giving one more value for k

  Posted by Charlie on 2012-06-29 16:14:23
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