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A104484 Number of distinct prime divisors of 33...331 (with n 3s). 5
1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 2, 2, 3, 1, 3, 4, 3, 2, 4, 3, 3, 2, 4, 3, 3, 2, 3, 4, 6, 2, 2, 3, 3, 4, 4, 1, 3, 3, 6, 6, 3, 2, 3, 5, 3, 1, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,8

COMMENTS

Interestingly, the first seven members in this sequence are all primes.

LINKS

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

EXAMPLE

Number of distinct prime divisors of 31 is 1 (prime).

Number of distinct prime divisors of 331 is 1 (prime).

Number of distinct prime divisors of 3331 is 1 (prime).

Number of distinct prime divisors of 33331 is 1 (prime).

Number of distinct prime divisors of 333331 is 1 (prime).

Number of distinct prime divisors of 3333331 is 1 (prime).

Number of distinct prime divisors of 33333331 is 1 (prime).

MATHEMATICA

Table[Length[FactorInteger[(10^(n + 1) - 7)/3]], {n, 1, 50}] (Steinerberger)

CROSSREFS

Sequence in context: A132328 A064822 A238337 * A038809 A078342 A177903

Adjacent sequences:  A104481 A104482 A104483 * A104485 A104486 A104487

KEYWORD

nonn

AUTHOR

Parthasarathy Nambi, Apr 18 2005

STATUS

approved

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Last modified September 22 12:52 EDT 2019. Contains 327307 sequences. (Running on oeis4.)