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%I #17 Dec 10 2019 04:03:17
%S 2,7,13,19,31,61,107,127,521,607,1279,3217,11213,21701,44497,132049,
%T 216091,756839,1257787,3021377,6972593,20996011,24036583,30402457,
%U 37156667,43112609
%N Odious Mersenne exponents.
%t Select[MersennePrimeExponent[Range[47]], OddQ @ DigitCount[#, 2][[1]] &] (* _Amiram Eldar_, Dec 10 2019 *)
%Y Intersection of A000043 and A027697.
%Y Cf. A000069, A174265.
%K nonn,base,more
%O 1,1
%A _Ilya Lopatin_ and _Juri-Stepan Gerasimov_, Feb 08 2014
%E a(13) and a(18) inserted and more terms added by _Amiram Eldar_, Dec 10 2019