12345...56781 (72-digits)

This number is a prime.

                                                                          12
3456790123 4567901234 5679012345 6790123456 7901234567 9012345679 0123456781

+ R(2)+R(3)+R(4)+ … +R(72) is prime, where R(n) is a repunit number. [Rivera]

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