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A104889 Number of distinct prime divisors of 44...447 (with n 4s). 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Also number of distinct prime factors of (10^(n + 1) - 1)*4/9 + 3. - Stefan Steinerberger, Feb 21 2006

LINKS

Table of n, a(n) for n=0..39.

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. A104564.

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

STATUS

approved

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Last modified April 18 08:37 EDT 2019. Contains 322209 sequences. (Running on oeis4.)