A061439 Largest number whose cube has n digits.

2, 4, 9, 21, 46, 99, 215, 464, 999, 2154, 4641, 9999, 21544, 46415, 99999, 215443, 464158, 999999, 2154434, 4641588, 9999999, 21544346, 46415888, 99999999, 215443469, 464158883, 999999999, 2154434690, 4641588833, 9999999999

Offset: 1

Author

Amarnath Murthy, May 03 2001

Keywords

• nonn
• base
• easy

Comments

a(n) + A181375(n) + A181377(n) + A181379(n) + A181381(n) + A181400(n) + A181402(n) + A181404(n) + A130130(n) = A002283(n).

Examples

			a(5) = 46 because 46^3 = 97336 has 5 digits, while 47^3 = 103823 has 6 digits.
		

Crossrefs

a(n) is one more than the corresponding term of A018005. Cf. A061435.

Programs

Maple

Digits := 100:
A061439 := n->ceil(10^(n/3))-1:
seq (A061439(n), n=1..40);

Mathematica

t={}; i=0; Do[i=i+1; While[IntegerLength[i^3]<=n,i++]; AppendTo[t,i-1],{n,20}]; t (* Jayanta Basu, May 19 2013 *)

Formula

a(n) = ceiling(10^(n/3)) - 1. - Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

Extensions

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

Typo in Maple program fixed by Martin Renner, Jan 31 2011