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 A034988 #6 Oct 06 2019 18:13:10
%S A034988 8,257,2581,2582,258198,2581988,8164966,25819889,816496581,8164965809,
%T A034988 258198889746,2581988897471,8164965809277,25819888974716,
%U A034988 258198889747161,816496580927726,81649658092772603,2581988897471611256,8164965809277260327
%N A034988 a(n) is root of smallest square starting with a string of n 'digit_6's.
%e A034988 a(5) = 258198^2 = {66666}207204.
%t A034988 For[ i = 1, i < 20, i++, zeros = 0; isFound = False; While[ !isFound, low = Ceiling[ Sqrt[ 2/3*(10^i - 1)*10^zeros ] ]; high = Floor[ Sqrt[ (2/3*(10^i - 1) + 1)*10^zeros ] ]; isFound = (low <= high); zeros++ ]; Print[ low, " ", low^2 ] ]
%Y A034988 Cf. A034989.
%K A034988 nonn,base
%O A034988 1,1
%A A034988 _Patrick De Geest_, Nov 15 1998
%E A034988 Program and more terms from Jonathan Cross (jcross(AT)wcox.com), Oct 15 2001