This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A346146 #11 Jul 13 2021 19:45:18 %S A346146 1,9,17,25,29,33,43,45,49,53,57,59,69,73,81,89,97,103,113,129,134,143, %T A346146 161,165,173,193,201,205,206,209,225,227,229,233,237,241,257,273,278, %U A346146 281,289,293,297,303,305,321,345,349,353,369,377,381,383,385,401,405 %N A346146 Numbers m such that there are no primes of the form 2^m + 2^k - 1, for 0 < k < m. %C A346146 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 A346146 q[m_] := AllTrue[Range[m - 1], ! PrimeQ[2^m + 2^# - 1] &]; Select[Range[400], q] (* _Amiram Eldar_, Jul 06 2021 *) %o A346146 (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 A346146 Cf. A081504. %K A346146 nonn %O A346146 1,2 %A A346146 _Lamine Ngom_, Jul 06 2021