A061433 Largest n-digit square.

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

Offset

1,1

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

Links

Table of n, a(n) for n=1..18.

Formula

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

Example

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

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 *)

Prog

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

Crossrefs

Cf. A061432.

Sequence in context: A180737 A068881 A104266 * A069659 A271556 A368446

Adjacent sequences: A061430 A061431 A061432 * A061434 A061435 A061436

Keyword

nonn,base,easy

Author

Amarnath Murthy, May 03 2001

Extensions

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

Status

approved