A017936 Smallest number whose square has n digits.

1, 4, 10, 32, 100, 317, 1000, 3163, 10000, 31623, 100000, 316228, 1000000, 3162278, 10000000, 31622777, 100000000, 316227767, 1000000000, 3162277661, 10000000000, 31622776602, 100000000000, 316227766017, 1000000000000

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• base
• easy

Examples

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

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A061432.

Programs

Magma

[Ceiling(10^((n-1)/2)): n in [1..30]]; // Vincenzo Librandi, Oct 21 2011

Maple

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

Mathematica

Table[Ceiling[Sqrt[10^n]],{n,0,30}] (* Harvey P. Dale, Jan 19 2012 *)

Formula

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

Extensions

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

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