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 A155854 #17 Aug 31 2025 21:26:44 %S A155854 1,3,4,5,6,7,9,10,11,12,13,14,15,17,18,19,21,22,23,24,25,26,27,29,30, %T A155854 31,33,34,35,36,37,38,39,41,42,43,44,45,47,48,49,51,52,53,54,55,56,57, %U A155854 59,60,61,63,64,65,66,67,69,70,71,72,73,74,75,77,78,79,80,81,83,84,85,86,87 %N A155854 Numbers k such that 13*k + 3 is not prime. %H A155854 Vincenzo Librandi, <a href="/A155854/b155854.txt">Table of n, a(n) for n = 1..1000</a> %t A155854 Select[Range[100], !PrimeQ[13 # + 3] &] %o A155854 (Magma) [n: n in [0..90] | not IsPrime(13*n + 3)]; // _Vincenzo Librandi_, Oct 15 2012 %Y A155854 Cf. A100202, A155853. %K A155854 nonn,easy,changed %O A155854 1,2 %A A155854 _Vincenzo Librandi_, Jan 29 2009 %E A155854 Data corrected by _Harvey P. Dale_, Sep 11 2011