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 A017936 Smallest number whose square has n digits. 15

%I

%S 1,4,10,32,100,317,1000,3163,10000,31623,100000,316228,1000000,

%T 3162278,10000000,31622777,100000000,316227767,1000000000,3162277661,

%U 10000000000,31622776602,100000000000,316227766017,1000000000000

%N Smallest number whose square has n digits.

%H Vincenzo Librandi, <a href="/A017936/b017936.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = ceiling(10^((n-1)/2)).

%e a(4) = 32, 32^2 = 1024 has 4 digits, while 31^2 = 961 has 3 digits.

%p A061436 := n->ceil(10^((n-1)/2));

%t Table[Ceiling[Sqrt[10^n]],{n,0,30}] (* _Harvey P. Dale_, Jan 19 2012 *)

%o (MAGMA) [Ceiling(10^((n-1)/2)): n in [1..30]]; // _Vincenzo Librandi_, Oct 21 2011

%Y Cf. A061432.

%K nonn,base,easy

%O 1,2

%A _N. J. A. Sloane_

%E More terms from Larry Reeves (larryr(AT)acm.org), May 16 2001

%E More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

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Last modified May 17 09:03 EDT 2021. Contains 343969 sequences. (Running on oeis4.)