1,2

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

Amiram Eldar, Table of n, a(n) for n = 1..201

a(n) = A001221(A173772(n+1)). - Amiram Eldar, Jan 27 2020

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).

Table[Length[FactorInteger[(10^(n + 1) - 1)*4/9 + 3]], {n, 1, 40}] (* Stefan Steinerberger, Feb 21 2006 *)

Cf. A001221, A104564, A173772.

Sequence in context: A283845 A058071 A174961 * A290979 A117910 A275435

Adjacent sequences: A104886 A104887 A104888 * A104890 A104891 A104892

nonn

Parthasarathy Nambi, Apr 24 2005

More terms from Stefan Steinerberger, Feb 21 2006

Offset corrected and more terms added by Amiram Eldar, Jan 27 2020

approved