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A004216 a(n) =  floor(log_10(n)). 23
0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,100

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = if n > 9 then a(floor(n / 10)) + 1 else 0. - Reinhard Zumkeller, Oct 31 2001

a(n) = floor(log_10(n)) = A055642(n) - 1. - L. Edson Jeffery, Jul 09 2014

G.f.: (1/(1 - x))*Sum_{k>=1} x^(10^k). - Ilya Gutkovskiy, Jan 08 2017

MATHEMATICA

Table[ Length[ IntegerDigits[n, 10] ] - 1, {n, 105}] (* Jean-Fran├žois Alcover, Jun 10 2013 *)

Table[Floor[Log10[n]], {n, 105}] (* L. Edson Jeffery, Jul 09 2014 *)

PROG

(Haskell)

a004216 n = if n <= 9 then 0 else 1 + a004216 (n `div` 10)

-- Reinhard Zumkeller, Dec 22 2012

CROSSREFS

Cf. A055642.

Sequence in context: A329030 A027388 A114295 * A076489 A211666 A297037

Adjacent sequences:  A004213 A004214 A004215 * A004217 A004218 A004219

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from James A. Sellers, Sep 19 2000

STATUS

approved

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Last modified August 14 08:08 EDT 2020. Contains 336480 sequences. (Running on oeis4.)