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 A165991 #7 Sep 08 2022 08:45:48 %S A165991 0,5,8,9,10,11,13,14,17,19,20,21,22,23,24,25,26,27,29,31,32,33,34,35, %T A165991 36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,56,57,58,59, %U A165991 60,61,62,63,64,65,66,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,85,86,87 %N A165991 Numbers n such that 3 + 2^n is not prime. %C A165991 Complement of A057732. %H A165991 Vincenzo Librandi, <a href="/A165991/b165991.txt">Table of n, a(n) for n = 1..1000</a> %e A165991 For n=0, 3+2^0=4 is not prime. n=5, 3+2^5=35=5*7, not prime. n=8, 3+2^8=259=7*37 not prime. %t A165991 Select[Range[0, 100], !PrimeQ[3 + 2^#] &] (* _Vincenzo Librandi_, Oct 15 2012 *) %o A165991 (Magma) [n: n in [0..100] |not IsPrime(3 + 2^n )]; // _Vincenzo Librandi_, Oct 15 2012 %K A165991 nonn,easy %O A165991 1,2 %A A165991 _Vincenzo Librandi_, Oct 03 2009 %E A165991 Entries checked - _R. J. Mathar_, Oct 05 2009