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 A280083 #14 Jan 16 2023 08:08:08 %S A280083 0,2,3,4,5,7,8,11,13,16,17,19,23,31,43,61,79,101,127,167,191,199,313, %T A280083 347,701,1709,2617,3539,5807,10501,10691,11279,12391,14479,42737, %U A280083 83339,95369,117239,127031,138937,141079,267017,269987,374321,986191,4031399 %N A280083 Numbers k such that (2^k + 1)/(2 - (-1)^k) is a prime. %t A280083 Select[Range[0, 10^3], PrimeQ[(2^# + 1)/(2 - (-1)^#)] &] (* _Michael De Vlieger_, Dec 25 2016 *) %Y A280083 Cf. A000978, A019434. %K A280083 nonn %O A280083 1,2 %A A280083 _Thomas Ordowski_, Dec 25 2016