A328687 - OEIS

%I #4 Oct 25 2019 13:06:03

%S -1,18,27,-1,36,38,44,35,-1,26,16,24,14,35,18,-1,19,35,24,36,27,12,26,

%T 51,-1,39,16,37,26,25,16,22,23,36,19,-1,25,25,25,40,57,56,24,11,24,21,

%U 23,26,-1,33,47,22,40,48,22,31,31,22,29,18,16,30,26,-1,24

%N a(n) is the number of decimals in sqrt(n) needed for all digits 0-9 to occur or -1 if n is a perfect square.

%C All positive terms are >= 10.

%e The decimals for sqrt(2) are .414213562373095048|801688724... and 18 decimals are needed for all digits to occur so a(2) = 18.

%e The decimals for sqrt(143) are .9582607431|01398021... so a(143) = 10.

%e The largest term when n < 10^9 is a(232863046) = 229.

%K sign,base

%O 1,2

%A _Lars Blomberg_, Oct 25 2019