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A216487

Smallest prime factor of n^(2n) - 1 having the form k*n+1.

3, 7, 5, 11, 7, 29, 17, 19, 11, 23, 13, 53, 29, 31, 17, 10949, 19, 108301, 41, 43, 23, 47, 73, 101, 53, 109, 29, 59, 31, 373, 257, 67, 103, 71, 37, 149, 191, 79, 41, 83, 43, 173, 89, 181, 47, 659, 97, 197, 101, 103, 53, 107, 109, 881, 113, 229, 59, 709, 61, 977

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OFFSET

2,1

COMMENTS

The corresponding values of k are in A216506.

LINKS

Amiram Eldar, Table of n, a(n) for n = 2..670

FORMULA

a(n) = Min{A187022(n), A187023(n)}.

EXAMPLE

a(7) = 29 because 7^14 - 1 = 2 ^ 4 * 3 * 29 * 113 * 911 * 4733 and the smallest prime divisor of the form k*n+1 is 29 = 4*7+1.

MATHEMATICA