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Message boards : PrimeSearchTeam message board : primes formed by concatenation of two consecutive Mersenne numbers

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paolo
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Joined: 1 Jun 19
Posts: 2
ID: 1134125
Credit: 12,292,842
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Message 130060 - Posted: 1 Jun 2019 | 19:53:05 UTC

Hallo i am searching for primes of the form 10^d*(2^k-1)+2^(k-1)-1 where k is a non negative integer and d is the number of decimal digits of 2^(k-1)-1 eg 12763, 255127, 40952047. Two posts on mathoverflow have received a lot of views because none of these primes up to k=800.000 is congruent to 6 mod 7 and everytime k is a multiple of 43, then k is also of the form 41s+r, with r in the set (1,10,16,18,37). Can you help me to find primes of this form at least up to k=10^6?
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Message boards : PrimeSearchTeam message board : primes formed by concatenation of two consecutive Mersenne numbers

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