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%I
%S 1,111111111,11111111111,1011111111111111101,1111111111111,
%T 10111111111111111,11100111111111111111111,101111111111111111101,
%U 111111111111111,1011111111111111111,1010111111111111111111101,1110011111111111111111111,10111111111111111111101,11101111111111111111111,11111111111111111,1111111111111111111010000,1111111111111111111111001
%N In base 2 dismal arithmetic, a(n) is the smallest number than has exactly n different square roots (or -1 if no such number exists).
%C The numbers are written in base 2.
%H D. Applegate, M. LeBrun and N. J. A. Sloane, <a href="http://arxiv.org/abs/1107.1130">Dismal Arithmetic</a>, Journal of Integer Sequences, Vol. 14 (2011), #11.9.8.
%H <a href="/index/Di#dismal">Index entries for sequences related to dismal arithmetic</a>
%e 111111111 has two square roots, 11011 and 11111;
%e 11111111111 has 3 square roots, 110111, 111011, 11111.
%Y Cf. A191701, A202174.
%K nonn,base
%O 1,2
%A _N. J. A. Sloane_, Dec 13 2011
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