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%I #11 Jul 13 2021 19:45:18
%S 1,9,17,25,29,33,43,45,49,53,57,59,69,73,81,89,97,103,113,129,134,143,
%T 161,165,173,193,201,205,206,209,225,227,229,233,237,241,257,273,278,
%U 281,289,293,297,303,305,321,345,349,353,369,377,381,383,385,401,405
%N Numbers m such that there are no primes of the form 2^m + 2^k - 1, for 0 < k < m.
%C In comparison with A081504 (dealing with 2^m + 2^k + 1) where most of the terms are even, here the vast majority of terms are odd.
%t q[m_] := AllTrue[Range[m - 1], ! PrimeQ[2^m + 2^# - 1] &]; Select[Range[400], q] (* _Amiram Eldar_, Jul 06 2021 *)
%o (PARI) isok(m) = for(k=1, m-1, if (ispseudoprime(2^m+2^k-1), return (0))); return (1); \\ _Michel Marcus_, Jul 06 2021
%Y Cf. A081504.
%K nonn
%O 1,2
%A _Lamine Ngom_, Jul 06 2021