OFFSET
0,4
COMMENTS
Number of distinct prime divisors of (n!)!, (A000197). - Jason Earls, Jul 04 2001
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
David Baugh, Table of n, a(n) for n = 0..25 (a(24)-a(25) found using Kim Walisch's primecount program).
Andrew R. Booker, The Nth Prime Page
Tomás Oliveira e Silva, Tables of values of pi(x) and of pi2(x)
R. G. Wilson v, Letter to N. J. A. Sloane, Oct. 1993
R. G. Wilson, V, Letter to N. J. A. Sloane, Oct. 1993
R. G. Wilson v, Letter to N. J. A. Sloane, Jan. 1994
MATHEMATICA
Table[PrimePi[n!], {n, 0, 16}]
PROG
(PARI) for(n=0, 10, print(omega(n!!)))
(PARI) a(n)=primepi(n!) \\ Charles R Greathouse IV, Jan 21 2016
(Sage) [prime_pi(factorial(n)) for n in range(0, 14)] # Zerinvary Lajos, Jun 06 2009
CROSSREFS
KEYWORD
hard,nonn
EXTENSIONS
a(15) from Jud McCranie
a(16)-a(17) from Paul Zimmermann
a(18) from Donovan Johnson, Dec 18 2009
a(19) from Donovan Johnson, Feb 18 2010
a(20) from Henri Lifchitz, Nov 11 2012
a(21)-a(23) from Henri Lifchitz, Aug 26 2014
STATUS
approved