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 A262102 #26 Jul 25 2021 02:40:11
%S A262102 4,444,1332,4221,11111,22131,23404,30031,42241,112443,133321,134421,
%T A262102 140122,140411,202401,214244,222223,224104,241121,304011,323131,
%U A262102 331401,402201,404041,411313,421411,434411,1001001,1001331,1010142,1032032,1140421,1212131,1224103,1233321,1302302,1302401,1414331,1421124,1440143
%N A262102 Pseudoprimes to base 5, written in base 5.
%H A262102 Amiram Eldar, <a href="/A262102/b262102.txt">Table of n, a(n) for n = 1..10000</a>
%F A262102 a(n) = A007091(A005936(n)).
%t A262102 base = 5; t = {}; n = 1;
%t A262102 While[Length[t] < 40, n++;
%t A262102 If[! PrimeQ[n] && PowerMod[base, n - 1, n] == 1,
%t A262102 AppendTo[t, FromDigits@IntegerDigits[n, 5]]]]; t
%o A262102 (PARI) lista(nn, b=5) = {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 A262102 Cf. A007091 (numbers in base 5), A005936 (pseudoprimes to base 5).
%Y A262102 Cf. A258189, A262101, A262103, A262104, A262105, A262154.
%K A262102 nonn,base
%O A262102 1,1
%A A262102 _Abdul Gaffar Khan_, Sep 11 2015