OFFSET
0,5
COMMENTS
From Bernard Schott, Nov 19 2021: (Start)
a(n) < n iff 2 <= n <= 38 or n = 40;
a(n) = n iff n = 1, 39, 41;
a(n) > n iff n = 0 or n >= 42. (End)
LINKS
FORMULA
MATHEMATICA
Array[IntegerLength[#!//.x_/; x~Mod~10==0:>x/10]&, 77, 0] (* Giorgos Kalogeropoulos, Nov 19 2021 *)
PROG
(Python)
from math import factorial
def A008906(n): return len(str(factorial(n)).rstrip('0')) # Chai Wah Wu, Oct 24 2021
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved