818752171

This number is a prime.

+ The smallest prime p such that the numbers 21 + 31 + 51 + 71 + 111 + ... + p1, 22 + 32 + 52 + 72 + 112 + ... + p2, 23 + 33 + 53 + 73 + 113 + ... + p3, 24 + 34 + 54 + 74 + 114 + ... + p4, 25 + 35 + 55 + 75 + 115 + ... + p5, are all primes. [Crespi de Valldaura]

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