0,3

Ray Chandler, Table of n, a(n) for n = 0..309 (from Kamada link)

Makoto Kamada, Factorizations of 100...001.

a(n) = A001221(A000533(n+1)). - R. J. Mathar, Aug 24 2011

The number of distinct prime factors of 11 is 1 since it is a prime.

The number of distinct prime factors of 101 is 1 since it is a prime.

The number of distinct prime factors of 1001 is 3.

The number of distinct prime factors of 10001 is 2.

A104223 := proc(n) 10^(n+1)+1 ; numtheory[factorset](%) ; nops(%) ; end proc: # R. J. Mathar, Aug 24 2011

Table[PrimeNu[FromDigits[Join[PadRight[{1}, n, 0], {1}]]], {n, 40}] (* Harvey P. Dale, Jul 18 2013 *)

Cf. A119704.

Sequence in context: A178250 A174550 A119704 * A057934 A058758 A122396

Adjacent sequences: A104220 A104221 A104222 * A104224 A104225 A104226

nonn

Parthasarathy Nambi, Apr 01 2005

More terms from Harvey P. Dale, Jul 18 2013

approved