X-Nico

Frank Nelson Cole

Édouard Lucas had demonstrated in 1876 that M₆₇ must have factors (i.e., is not prime), however he was unable to determine what those factors were.

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In fact a larger prime, 2¹²⁷ − 1, was found in 1876 by Lucas, and in 1883 Pervushin found the prime 2⁶¹ − 1.

see also