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
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
CROSSREFS
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