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 A074109 #11 Mar 23 2020 21:20:31
%S A074109 2,10,101,1001,10001,100001,1000001,10000001,100000001,1000000001,
%T A074109 10000000001,100000000002,1000000000001,10000000000001,
%U A074109 100000000000001,1000000000000001,10000000000000001,100000000000000001
%N A074109 Smallest n-digit squarefree number.
%C A074109 For n>=3, a(n) = 10^(n-1)+1 unless n-1 is in A086982. - _Robert Israel_, Mar 23 2020
%t A074109 Join[{2}, Table[x = 10^n; k = 0; While[! SquareFreeQ[y = x + k], k++]; y, {n, 19}]] (* _Jayanta Basu_, Aug 01 2013 *)
%Y A074109 Cf. A074110, A086982.
%K A074109 base,nonn
%O A074109 1,1
%A A074109 _Amarnath Murthy_, Aug 26 2002
%E A074109 More terms from _Matthew Conroy_, Aug 27 2002