OFFSET
1,3
FORMULA
a(n) = A062602(n!).
EXAMPLE
For n = 4: 4! = 24 = 23+1 = 2+22 = 3+21, so a(4) = 3.
PROG
(PARI) a(n) = {my(c = 0, m = n!); forprime(p = 2, m-1, if(!isprime(m - p), c++)); c; } \\ Amiram Eldar, Jul 17 2024
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Labos Elemer, Jul 05 2001
EXTENSIONS
a(9)-a(13) from Sean A. Irvine, Mar 26 2023
a(14)-a(15) from Amiram Eldar, Jul 17 2024
STATUS
approved