login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A090617 Exponent of highest power of 8 dividing n!. 7
0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 13, 13, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 18, 18, 18, 18, 19, 19, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23, 24, 24, 24, 24 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,9
LINKS
FORMULA
a(n) = A090622(n, 8) = floor(A011371(n)/3) = floor((floor(n/2) + floor(n/4) + floor(n/8) + floor(n/16) + ...)/3).
a(n) = A244413(n!) . - R. J. Mathar, Jul 08 2021
EXAMPLE
a(8)=2 since 8! = 40320 = 8^2 * 630.
MATHEMATICA
Table[IntegerExponent[n!, 8], {n, 0, 80}] (* Harvey P. Dale, Mar 21 2013 *)
PROG
(Python 3.10+)
def A090617(n): return (n-bin(n).count('1'))//3 # Chai Wah Wu, Jul 09 2022
(PARI) a(n) = valuation(n!, 8); \\ Michel Marcus, Jul 10 2022
CROSSREFS
Sequence in context: A132011 A363822 A054893 * A053693 A330324 A341132
KEYWORD
nonn
AUTHOR
Henry Bottomley, Dec 06 2003
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)