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 A104889 Number of distinct prime divisors of 44...447 (with n 4s). 3
 1, 2, 1, 2, 3, 2, 2, 4, 1, 3, 2, 3, 2, 2, 2, 2, 3, 3, 1, 5, 4, 4, 4, 7, 1, 4, 2, 5, 3, 3, 3, 3, 3, 6, 4, 5, 3, 2, 3, 5, 6, 7, 4, 4, 4, 2, 5, 3, 3, 6, 4, 6, 2, 5, 3, 5, 3, 6, 4, 6, 4, 6, 3, 5, 6, 6, 4, 5, 2, 4, 7, 7, 3, 5, 3, 3, 3, 5, 4, 10, 5, 4, 3, 5, 3, 2, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Also number of distinct prime factors of (10^(n + 1) - 1)*4/9 + 3. - Stefan Steinerberger, Feb 21 2006 LINKS Amiram Eldar, Table of n, a(n) for n = 1..201 FORMULA a(n) = A001221(A173772(n+1)). - Amiram Eldar, Jan 27 2020 EXAMPLE Number of distinct prime divisors of 47 is 1 (prime). Number of distinct prime divisors of 447 is 2. Number of distinct prime divisors of 4447 is 1 (prime). MATHEMATICA Table[Length[FactorInteger[(10^(n + 1) - 1)*4/9 + 3]], {n, 1, 40}] (* Stefan Steinerberger, Feb 21 2006 *) CROSSREFS Cf. A001221, A104564, A173772. Sequence in context: A283845 A058071 A174961 * A290979 A117910 A275435 Adjacent sequences:  A104886 A104887 A104888 * A104890 A104891 A104892 KEYWORD nonn AUTHOR Parthasarathy Nambi, Apr 24 2005 EXTENSIONS More terms from Stefan Steinerberger, Feb 21 2006 Offset corrected and more terms added by Amiram Eldar, Jan 27 2020 STATUS approved

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Last modified April 5 10:33 EDT 2020. Contains 333239 sequences. (Running on oeis4.)