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A104890 Number of distinct prime divisors of 66...661 (with n 6s). 1
1, 1, 1, 3, 2, 2, 2, 4, 1, 2, 3, 2, 3, 3, 2, 4, 1, 3, 2, 1, 1, 2, 4, 2, 3, 4, 1, 4, 4, 4, 3, 2, 4, 3, 3, 4, 3, 5, 3, 7, 2, 1, 3, 4, 3, 6, 3, 6, 4, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Also number of distinct prime factors of 6/9*(10^(n + 1) - 1) - 5. - Stefan Steinerberger, Feb 26 2006

LINKS

Table of n, a(n) for n=0..49.

EXAMPLE

Number of distinct prime divisors of 61 is 1 (prime).

Number of distinct prime divisors of 661 is 1 (prime).

Number of distinct prime divisors of 6661 is 1 (prime).

MATHEMATICA

Table[Length[FactorInteger[6/9*(10^(n + 1) - 1) - 5]], {n, 1, 50}] (* Stefan Steinerberger, Feb 26 2006 *)

CROSSREFS

Cf. A104564.

Sequence in context: A067279 A106267 A096101 * A064123 A024703 A102845

Adjacent sequences:  A104887 A104888 A104889 * A104891 A104892 A104893

KEYWORD

nonn

AUTHOR

Parthasarathy Nambi, Apr 24 2005

EXTENSIONS

More terms from Stefan Steinerberger, Feb 26 2006

STATUS

approved

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Last modified May 26 17:17 EDT 2019. Contains 323597 sequences. (Running on oeis4.)