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 A153238 #39 Sep 08 2022 08:45:39
%S A153238 3,6,9,11,12,15,16,18,21,23,24,26,27,30,31,33,36,37,39,41,42,44,45,46,
%T A153238 48,51,54,56,57,58,59,60,61,63,65,66,69,70,71,72,75,76,78,79,81,83,84,
%U A153238 86,87,90,91,92,93,96,99,100,101,102,103,105,106,107,108,109,111,114
%N A153238 Numbers k such that 2*k + 3 is composite.
%C A153238 One less than the associated value in A047845. - _R. J. Mathar_, Jan 05 2011
%H A153238 Vincenzo Librandi, <a href="/A153238/b153238.txt">Table of n, a(n) for n = 1..10000</a>
%H A153238 Marc Wolf, François Wolf, <a href="https://hal.archives-ouvertes.fr/hal-01832624 ">Representation theorem of composite odd numbers indices</a>, SCIREA Journal of Mathematics (2018) 3.3, 106-117.
%F A153238 a(n) ~ n. - _Charles R Greathouse IV_, Dec 28 2011
%t A153238 lst={};Do[If[ !PrimeQ[2*n+3],AppendTo[lst,n]],{n,6!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Jan 10 2009 *)
%t A153238 Select[Range[120], CompositeQ[2 # + 3] &] (* _Michael De Vlieger_, Oct 17 2018 *)
%o A153238 (PARI) for(n=1,115,if(!isprime(2*n+3),print1(n,", "))) \\ _Joerg Arndt_, Dec 19 2010
%o A153238 (Magma) [ n: n in [0..120] | not IsPrime(2*n+3) ]; // _Klaus Brockhaus_, Dec 19 2010
%Y A153238 Cf. A067076, A047845, A144562.
%K A153238 nonn,easy
%O A153238 1,1
%A A153238 _Vincenzo Librandi_, Dec 21 2008
%E A153238 Edited by _Ray Chandler_, Jan 07 2009