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Integers k for which the k-th Mersenne prime exponent is a Gaussian prime (3 mod 4).
2

%I #12 Jan 21 2019 19:01:55

%S 2,4,7,8,11,12,14,15,16,20,28,29,31,32,34,40,41,42,45

%N Integers k for which the k-th Mersenne prime exponent is a Gaussian prime (3 mod 4).

%e A000043(45) = 37156667 is congruent to 3 mod 4, so 45 is in this sequence.

%e A000043(46) = 42643801 is congruent to 1 mod 4, so 46 is not in this sequence.

%t Select[Range@ 45, Mod[MersennePrimeExponent@ #, 4] == 3 &] (* _Michael De Vlieger_, Jul 22 2018 *)

%Y Cf. A000043, A112633, A112634, A112649.

%K nonn

%O 1,1

%A _Jorge Coveiro_, Dec 27 2005

%E Edited by _Don Reble_, Jan 25 2006

%E More terms from _Gord Palameta_, Jul 21 2018