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 A192992 #10 Oct 22 2024 03:27:27 %S A192992 7,11,15,17,19,23,27,29,31,35,39,41,43,47,49,51,55,59,63,65,67,69,71, %T A192992 75,77,79,83,87,91,95,97,99,101,103,109,111,113,115,119,123,127,129, %U A192992 131,135,137,139,143,147,151,153,155,159,163,167,169,171,173,175 %N A192992 Odd n > 1 such that n+1 is a semiprime times a power of two. %C A192992 Odd n such that n+1 is in A192991. %C A192992 This is to thin numbers A192868 as semiprimes A001358 are to primes A000040. %F A192992 a(n) = A192991(n) - 1. %e A192992 239 is in the sequence because 239+1 = 240 = 6th semiprime * 2^4 = 3 * 5 * 16. %Y A192992 Cf. A005408, A001358, A192868, A192991. %K A192992 nonn,easy %O A192992 1,1 %A A192992 _Jonathan Vos Post_, Jul 13 2011