251

This number is a prime.

Just showing those entries submitted by 'Capelle': (Click here to show all)

+ All the prime numbers up to 251, without repetition, appear in Benjamin Franklin's original 16-by-16 square. [Capelle]

+ Its square is the smallest number n for which the Ramanujan tau-function tau(n) is prime. It was found by D. H. Lehmer in 1965. [Capelle]

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