OFFSET
2
COMMENTS
This sequence is not the same as A143731 and first departs from it when n = 210. The characteristic function A143731(210)=1, while a(210)=2. This is because 210 is the smallest number with 4 distinct prime factors (210 = 2*3*5*7) and 4 is the smallest composite number. Thus, Omega(omega(210)) = Omega(4) = 2.
The records for this sequence are at 2, 6, 210, 9699690, 32589158477190044730, ..., the products of the first 2^n primes. - Charles R Greathouse IV, Sep 14 2015
LINKS
G. C. Greubel, Table of n, a(n) for n = 2..5000
FORMULA
a(n) << log log n. - Charles R Greathouse IV, Sep 14 2015
MATHEMATICA
Table[PrimeOmega[PrimeNu[n]], {n, 2, 100}]
PROG
(PARI) a(n)=bigomega(omega(n)) \\ Charles R Greathouse IV, Sep 14 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jun 15 2014
STATUS
approved