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 A068538 #19 Apr 29 2022 20:32:12
%S A068538 111111111,111111111111111111,1111111111111111111111,
%T A068538 111111111111111111111111111,111111111111111111111111111111111111,
%U A068538 111111111111111111111111111111111111111111,11111111111111111111111111111111111111111111,111111111111111111111111111111111111111111111
%N A068538 Nonsquarefree repunits.
%C A068538 The number of digits of these repunits form the sequence A046412. - _Michel Marcus_, Nov 24 2013
%F A068538 a(n) = (10^A046412(n) - 1) / 9. - _Max Alekseyev_, Apr 29 2022
%o A068538 (PARI) lista(nn) = {for (n=1, nn, if (! issquarefree(r = sum(i=0, n, 10^i)), print1(r, ", ")););} \\ _Michel Marcus_, Nov 24 2013
%K A068538 nonn
%O A068538 1,1
%A A068538 _Benoit Cloitre_, Mar 22 2002