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A145044
Primes p (A000043) such that 2^p-1 is prime (A000668) and congruent to 271 mod 6!.
4
13, 61, 2281, 3217, 23209, 44497, 132049, 13466917, 30402457, 42643801
OFFSET
1,1
COMMENTS
Mersenne numbers (with the exception of the first two) are congruent to 31, 127, 271, 607 mod 6!. This sequence is a subsequence of A000043.
MATHEMATICA
Select[MersennePrimeExponent[Range[47]], PowerMod[2, #, 6!] == 272 &] (* Amiram Eldar, Mar 22 2020 *)
KEYWORD
nonn,more
AUTHOR
Artur Jasinski, Sep 30 2008
EXTENSIONS
a(10) from Amiram Eldar, Mar 22 2020
STATUS
approved