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 A262103 #26 Jul 25 2021 02:40:18
%S A262103 55,505,1001,1221,2121,5041,5051,5501,10101,12001,15225,20301,21021,
%T A262103 23501,24301,24341,30041,31031,32451,42241,50125,50321,101101,102421,
%U A262103 105131,111111,113425,121001,121101,123041,123321,132305,150135,152021,201201,204445,212121,221001,222401,232401
%N A262103 Pseudoprimes to base 6, written in base 6.
%H A262103 Amiram Eldar, <a href="/A262103/b262103.txt">Table of n, a(n) for n = 1..10000</a>
%F A262103 a(n) = A007092(A005937(n)).
%t A262103 base = 6; t = {}; n = 1;
%t A262103 While[Length[t] < 40, n++;
%t A262103 If[! PrimeQ[n] && PowerMod[base, n - 1, n] == 1,
%t A262103 AppendTo[t, FromDigits@IntegerDigits[n, 6]]]]; t
%o A262103 (PARI) lista(nn, b=6) = {for (n=1, nn, if (Mod(b, n)^(n-1)==1 && !ispseudoprime(n) && n>1, print1(subst(Pol(digits(n,b), x), x, 10), ", ");););} \\ _Michel Marcus_, Sep 30 2015
%Y A262103 Cf. A007092 (numbers in base 6), A005937 (pseudoprimes to base 6).
%Y A262103 Cf. A258189, A262101, A262102, A262104, A262105, A262154.
%K A262103 nonn,base
%O A262103 1,1
%A A262103 _Abdul Gaffar Khan_, Sep 11 2015