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 A153039 #23 Jul 14 2025 17:49:23 %S A153039 8,11,14,16,17,20,21,23,26,28,29,31,32,35,36,38,41,42,44,46,47,49,50, %T A153039 51,53,56,59,61,62,63,64,65,66,68,70,71,74,75,76,77,80,81,83,84,86,88, %U A153039 89,91,92,95,96,97,98,101,104,105,106,107,108,110,111,112 %N A153039 Numbers k such that 2*k-7 is composite. %C A153039 Two more than the associated value in A153043, one more than in A153040. %H A153039 Vincenzo Librandi, <a href="/A153039/b153039.txt">Table of n, a(n) for n = 1..1000</a> %t A153039 Select[Range[8,200], !PrimeQ[2*#-7]&] (* _Vladimir Joseph Stephan Orlovsky_, Feb 09 2012 *) %o A153039 (Magma) [n: n in [5..220]| not IsPrime(2*n-7)]; %o A153039 (PARI) list(n)=apply(k->(k+7)/2,setminus(vector(n,k,2*k+7), primes(primepi(2*n+7)))) \\ _Charles R Greathouse IV_, May 14 2012 %Y A153039 Complement of A089192, A153040. %K A153039 nonn,easy %O A153039 1,1 %A A153039 _Vincenzo Librandi_, Dec 17 2008 %E A153039 Partially edited by _N. J. A. Sloane_, Jun 23 2010