A062153 a(n) = floor(log_3(n)).

0, 0, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4

Offset: 1

Author

Henry Bottomley, Jun 06 2001

Keywords

• easy
• nonn

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000244, A000523, A007089, A102572.

Programs

Magma

[ Ilog(3,n) : n in [1..100] ]; // N. J. A. Sloane, Dec 23 2006

Mathematica

Floor[Log[3,Range[120]]]  (* Harvey P. Dale, Apr 30 2011 *)

PARI

a(n)=logint(n,3) \\ Charles R Greathouse IV, Nov 15 2022

Formula

a(n) = (number of digits of n when written in base 3) - 1.

a(n) = if n > 2 then a(floor(n / 3)) + 1 else 0. - Reinhard Zumkeller, Oct 29 2001

G.f.: (1/(1 - x))*Sum_{k>=1} x^(3^k). - Ilya Gutkovskiy, Jan 08 2017