OFFSET
0,7
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..10000
FORMULA
a(n) = A090622(n, 4) = floor(A011371(n)/2) = floor((floor(n/2) + floor(n/4) + floor(n/8) + floor(n/16) + ...)/2).
a(n) = A235127(n!). - R. J. Mathar, Jul 08 2021
EXAMPLE
a(6)=2 since 6! = 720 = 4^2 * 45.
MATHEMATICA
IntegerExponent[Range[0, 100]!, 4] (* Vincenzo Librandi, Mar 10 2013 *)
PROG
(PARI) a(n) = valuation( n!, 4 ); /* Joerg Arndt, Mar 10 2013 */
(Python 3.10+)
def A090616(n): return (n-n.bit_count())>>1 # Chai Wah Wu, Jul 09 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Henry Bottomley, Dec 06 2003
STATUS
approved