A346146 Numbers m such that there are no primes of the form 2^m + 2^k - 1, for 0 < k < m.

1, 9, 17, 25, 29, 33, 43, 45, 49, 53, 57, 59, 69, 73, 81, 89, 97, 103, 113, 129, 134, 143, 161, 165, 173, 193, 201, 205, 206, 209, 225, 227, 229, 233, 237, 241, 257, 273, 278, 281, 289, 293, 297, 303, 305, 321, 345, 349, 353, 369, 377, 381, 383, 385, 401, 405

Offset

1,2

Comments

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.

Links

Table of n, a(n) for n=1..56.

Mathematica

q[m_] := AllTrue[Range[m - 1], ! PrimeQ[2^m + 2^# - 1] &]; Select[Range[400], q] (* Amiram Eldar, Jul 06 2021 *)

Prog

(PARI) isok(m) = for(k=1, m-1, if (ispseudoprime(2^m+2^k-1), return (0))); return (1); \\ Michel Marcus, Jul 06 2021

Crossrefs

Cf. A081504.

Sequence in context: A317332 A073160 A242987 * A143850 A017077 A004768

Adjacent sequences: A346143 A346144 A346145 * A346147 A346148 A346149

Keyword

nonn

Author

Lamine Ngom, Jul 06 2021

Status

approved