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

1,1

Comments

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

Links

Table of n, a(n) for n=1..30.

Formula

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

Example

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

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 *)

Crossrefs

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

Sequence in context: A332800 A093698 A091619 * A351644 A027711 A307548

Adjacent sequences: A061436 A061437 A061438 * A061440 A061441 A061442

Keyword

nonn,base,easy

Author

Amarnath Murthy, May 03 2001

Extensions

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

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

Status

approved