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 A155935 #13 Sep 08 2022 08:45:41 %S A155935 1,3,4,5,7,9,10,11,12,13,14,15,16,17,19,20,21,22,23,25,26,27,28,29,30, %T A155935 31,33,34,35,36,37,39,40,41,42,43,45,46,47,48,49,50,51,52,53,54,55,57, %U A155935 58,59,60,61,63,64,65,67,68,69,70,71,73,75,76,77,79,80,81 %N A155935 Numbers n such that 13*n + 5 is not prime. %H A155935 Vincenzo Librandi, <a href="/A155935/b155935.txt">Table of n, a(n) for n = 1..1000</a> %e A155935 Distribution of the even terms in the following triangular array:: %e A155935 *; %e A155935 *,*; %e A155935 *,*,*; %e A155935 *,*,*,*; %e A155935 *,*,*,*,*; %e A155935 *,*,*,*,*,*; %e A155935 *,*,*,10,*,*,*; %e A155935 *,*,*,*,14,*,*,*; %e A155935 4,*,*,*,*,*,*,*,*; %e A155935 *,*,*,*,*,*,*,*,*,*; %e A155935 *,*,12,*,*,*,*,*,*,*,*; %e A155935 *,*,*,*,*,*,*,*,*,40,*,*; etc. %e A155935 where * marks the non-integer values of (4*h*k + 2*k + 2*h - 4)/13 with h >= k >= 1. - _Vincenzo Librandi_, Jan 15 2013 %t A155935 Select[Range[0, 100], !PrimeQ[13 # + 5] &] (* _Vincenzo Librandi_, Oct 15 2012 *) %o A155935 (Magma) [n: n in [0..90] | not IsPrime(13*n + 5)]; %Y A155935 Cf. A102732, A154610. %K A155935 nonn,easy %O A155935 1,2 %A A155935 _Vincenzo Librandi_, Jan 31 2009