OFFSET
1,2
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..83
FORMULA
A025487(a(n)) = n!. - Amiram Eldar, Jun 20 2019
EXAMPLE
A025487(34) = 720 = 6! so a(6) = 34. - David A. Corneth, Sep 19 2019
PROG
(Python)
from itertools import count
from functools import lru_cache
from math import factorial
from sympy import prime, integer_log, primorial
def A098718(n):
@lru_cache(maxsize=None)
def g(x, m, j): return sum(g(x//(prime(m)**i), m-1, i) for i in range(j, integer_log(x, prime(m))[0]+1)) if m-1 else max(0, x.bit_length()-j)
c, f = 1, factorial(n)
for k in count(1):
if primorial(k)>f:
break
c += g(f, k, 1)
return c # Chai Wah Wu, Mar 23 2026
CROSSREFS
KEYWORD
nonn
AUTHOR
Jeff Burch, Sep 29 2004
EXTENSIONS
More terms from Amiram Eldar, Jun 20 2019
a(35) corrected by Amiram Eldar, Jul 26 2019
a(36)-a(39) from David A. Corneth, Sep 19 2019
STATUS
approved