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 A004218 log_10(n) rounded up. 8
 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,11 COMMENTS a(n) is the number of terms in the sequence A011557 (Powers of 10) that are less than n. For n > 1, a(n) is the number of digits in n-1. - Tanya Khovanova, Jun 22 2007 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 FORMULA a(n) = if n == 1 then 0 else 1 + A004216(n-1). - Reinhard Zumkeller, Dec 22 2012 a(n) = A055642(n-1) for all n > 1. a(n+1) is the number of decimal digits of n if 0 is considered to have 0 digits. - M. F. Hasler, Dec 07 2018 EXAMPLE From M. F. Hasler, Dec 07 2018: (Start) log_10(1) = 0, therefore a(1) = 0. log_10(2) = 0.301..., therefore a(2) = 1. log_10(9) = 0.954..., therefore a(9) = 1. log_10(10) = 1, therefore a(10) = 1. log_10(11) = 1.04..., therefore a(11) = 2. log_10(99) = 1.9956..., therefore a(99) = 2. log_10(100) = 2, therefore a(100) = 2. log_10(101) = 2.004..., therefore a(101) = 3. (End) MATHEMATICA Array[Ceiling[Log10[#]] &, 100] (* Amiram Eldar, Dec 08 2018 *) PROG (Haskell) a004218 n = if n == 1 then 0 else 1 + a004216 (n - 1) (PARI) A004218(n)=logint(n-(n>1), 10)+1 \\ M. F. Hasler, Dec 07 2018 CROSSREFS Cf. A004216, A007953, A055642. Sequence in context: A231560 A113679 A262438 * A044931 A178487 A280560 Adjacent sequences:  A004215 A004216 A004217 * A004219 A004220 A004221 KEYWORD nonn AUTHOR STATUS approved

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Last modified September 23 03:32 EDT 2020. Contains 337291 sequences. (Running on oeis4.)