OFFSET
1,4
LINKS
FORMULA
EXAMPLE
a(5) = 14, because !5 = 44 and the number of primes up to 44 is 14.
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Shyam Sunder Gupta, Feb 11 2007
EXTENSIONS
a(17)-a(20) from Jens Kruse Andersen, Jul 18 2014
a(21)-a(23) using Kim Walisch's primecount, from Amiram Eldar, Aug 25 2020
STATUS
approved