OFFSET
1,8
FORMULA
a(n) = floor((n-A000720(n))/2). - Chai Wah Wu, Nov 14 2024
EXAMPLE
c_1 = 4 and c_3 = 8 are <= 9, so a(9) = 2.
PROG
(Python)
from sympy import primepi
def A377899(n): return n-primepi(n)>>1 # Chai Wah Wu, Nov 14 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 14 2024
STATUS
approved