OFFSET
0,4
EXAMPLE
a(3) = 4 because there are 4 primes less than A005867(3) = 8: 2, 3, 5 and 7.
PROG
(Python)
from sympy import prime, primepi
p = 1
l = [0]
for i in range(1, 12):
p *= (prime(i) - 1)
l.append(primepi(p))
print(l)
(PARI) A372730(n) = primepi(prod(k=1, n, prime(k)-1)); \\ Antti Karttunen, May 22 2024
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Alexandre Herrera, May 11 2024
EXTENSIONS
a(9)-a(11) from Antti Karttunen, May 22 2024
a(12)-a(16) from Amiram Eldar, May 22 2024
a(17)-a(18) from Chai Wah Wu, Jun 04 2024
a(19) from Chai Wah Wu, Jun 05 2024
STATUS
approved