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 A020142 #21 Jun 13 2018 03:35:38
%S A020142 15,39,65,195,481,561,781,793,841,985,1105,1111,1541,1891,2257,2465,
%T A020142 2561,2665,2743,3277,5185,5713,6501,6533,6541,7107,7171,7449,7543,
%U A020142 7585,8321,9073,10585,12403,12505,12545,12805,12871,13429,14111,14689,15067,15457
%N A020142 Pseudoprimes to base 14.
%C A020142 Composite numbers n such that 14^(n-1) == 1 (mod n). - _Michel Lagneau_, Feb 18 2012
%H A020142 T. D. Noe, <a href="/A020142/b020142.txt">Table of n, a(n) for n = 1..1000</a>
%H A020142 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>
%p A020142 select(t -> not isprime(t) and 14 &^ (t-1) mod t = 1, [seq(i,i=3..20000,2)]); # _Robert Israel_, Jun 12 2018
%t A020142 pseudos14 = {}; n = 1; While[Length[pseudos14] < 100, n++; If[!PrimeQ[n] && PowerMod[14, n - 1, n] == 1, AppendTo[pseudos14, n]]]; pseudos14 (* _T. D. Noe_, Feb 21 2012 *)
%Y A020142 Cf. A001567 (pseudoprimes to base 2).
%K A020142 nonn
%O A020142 1,1
%A A020142 _David W. Wilson_