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A105068 Number of distinct prime divisors of 10^n - 3. 4
1, 1, 1, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 4, 4, 1, 4, 5, 4, 2, 2, 4, 2, 2, 3, 4, 3, 4, 3, 6, 4, 3, 2, 4, 4, 5, 3, 5, 5, 4, 5, 7, 4, 5, 4, 7, 5, 4, 4, 5, 4, 3, 2, 4, 4, 2, 5, 5, 4, 4, 3, 3, 4, 2, 3, 5, 5, 6, 5, 4, 3, 3, 5, 6, 5, 5, 4, 7, 4, 3, 5, 4, 5, 5, 2, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..121

FORMULA

a(n) = A001221(A173833(n)). - Amiram Eldar, Jan 25 2020

EXAMPLE

If n = 1, 2 or 3, then 10^n - 3 is prime and thus the first three terms are 1.

MATHEMATICA

Table[Length[FactorInteger[10^n - 3]], {n, 1, 50}] (* Stefan Steinerberger, Feb 21 2006 *)

CROSSREFS

Cf. A001221, A173833.

Sequence in context: A183027 A078178 A306396 * A120676 A184172 A125973

Adjacent sequences:  A105065 A105066 A105067 * A105069 A105070 A105071

KEYWORD

nonn

AUTHOR

Parthasarathy Nambi, Apr 05 2005

EXTENSIONS

More terms from Stefan Steinerberger, Feb 21 2006

More terms from Amiram Eldar, Jan 25 2020

STATUS

approved

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Last modified April 15 20:40 EDT 2021. Contains 342977 sequences. (Running on oeis4.)