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 A074110 #8 Oct 03 2014 11:22:41
%S A074110 7,97,998,9998,99998,999997,9999998,99999998,999999998,9999999998,
%T A074110 99999999998,999999999998,9999999999998,99999999999998,
%U A074110 999999999999998,9999999999999998,99999999999999998,999999999999999998
%N A074110 Largest n-digit squarefree number.
%t A074110 Table[x = 10^n; k = -1; While[! SquareFreeQ[y = x + k], k += -1]; y, {n, 18}] (* _Jayanta Basu_, Aug 01 2013 *)
%Y A074110 Cf. A074109.
%K A074110 base,nonn
%O A074110 1,1
%A A074110 _Amarnath Murthy_, Aug 26 2002
%E A074110 More terms from _Matthew Conroy_, Aug 27 2002