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%I #18 Sep 04 2023 15:27:20
%S 13,61,2281,3217,23209,44497,132049,13466917,30402457,42643801
%N Primes p (A000043) such that 2^p-1 is prime (A000668) and congruent to 271 mod 6!.
%C 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.
%t Select[MersennePrimeExponent[Range[47]], PowerMod[2, #, 6!] == 272 &] (* _Amiram Eldar_, Mar 22 2020 *)
%Y Cf. A000043, A000668, A124477, A139484, A145038, A112633, A145041, A145042, A145044, A145045, A145046.
%K nonn,more
%O 1,1
%A _Artur Jasinski_, Sep 30 2008
%E a(10) from _Amiram Eldar_, Mar 22 2020
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