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A104223 Number of distinct prime factors of 1000..01 (with n zeros). 2
1, 1, 3, 2, 2, 2, 2, 2, 5, 3, 4, 3, 3, 4, 7, 5, 4, 3, 2, 4, 7, 4, 5, 3, 5, 3, 7, 4, 3, 7, 2, 4, 8, 4, 5, 6, 4, 3, 9, 4, 3, 7, 4, 4, 12, 4, 4, 9, 4, 7, 8, 4, 2, 6, 9, 5, 6, 5, 4, 6, 3, 3, 11, 3, 6, 8, 2, 4, 10, 11, 3, 5, 4, 7, 11, 6, 11, 7, 4, 9, 11, 3, 7, 8, 8, 3, 8, 4, 4, 11, 6, 4, 8, 4, 6, 8, 4, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

Makoto Kamada, Factorizations of 100...001.

FORMULA

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

EXAMPLE

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.

MAPLE

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

MATHEMATICA

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

CROSSREFS

Cf. A119704.

Sequence in context: A178250 A174550 A119704 * A057934 A058758 A122396

Adjacent sequences:  A104220 A104221 A104222 * A104224 A104225 A104226

KEYWORD

nonn

AUTHOR

Parthasarathy Nambi, Apr 01 2005

EXTENSIONS

More terms from Harvey P. Dale, Jul 18 2013

STATUS

approved

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Last modified May 28 09:52 EDT 2020. Contains 334679 sequences. (Running on oeis4.)