A061433 Largest n-digit square.

9, 81, 961, 9801, 99856, 998001, 9998244, 99980001, 999950884, 9999800001, 99999515529, 999998000001, 9999995824729, 99999980000001, 999999961946176, 9999999800000001, 99999999989350756, 999999998000000001

Offset: 1

Author

Amarnath Murthy, May 03 2001

Keywords

• nonn
• base
• easy

Comments

When (if ever) does this differ from A069659?

Trivially, 81 is both a square and a fourth power. Assuming my program works, there are no differences in the first 1500 terms. - Hans Havermann, Aug 06 2006

Examples

			a(4) = 9801 = 99^2 has 4 digits while 100^2 = 10000 has 5 digits.
		

Crossrefs

Cf. A061432.

Programs

Maple

A061433 := n->(ceil(10^(n/2))-1)^2;

Mathematica

Table[Floor[Sqrt[10^n-1]]^2,{n,20}] (* Harvey P. Dale, Aug 21 2014 *)

Python

from math import isqrt
def A061433(n): return isqrt(10**n-1)**2 # Chai Wah Wu, Feb 20 2023

Formula

a(n) = (ceiling(10^(n/2)) - 1)^2. - Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

Extensions

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