A004219 a(n) = floor(10*log_10(n)).

0, 3, 4, 6, 6, 7, 8, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Formula

a(n) = floor(10*log_10(n)) = floor(10(log(n)/log(10))) =

floor(10(log(n)/(log(2) + log(5)))). - Alonso del Arte, Dec 24 2013

Example

a(2) = 3 because 10(log(2)/log(10)) = 3.0102999566398...
a(3) = 4 because 10(log(3)/log(10)) = 4.7712125471966...
a(4) = 6 because 10(log(4)/log(10)) = 6.0205999132796...

Mathematica

Table[Floor[10Log[10, n]], {n, 75}] (* Alonso del Arte, Dec 24 2013 *)

Crossrefs

Cf. A004234.

Sequence in context: A160095 A135319 A329193 * A077542 A325611 A263842

Adjacent sequences: A004216 A004217 A004218 * A004220 A004221 A004222

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms from Alonso del Arte, Dec 24 2013

Status

approved