OFFSET
1,4
COMMENTS
This sequence is a second approximation of a double factorial analog to Stirling's approximation to factorial. Note that a(n) is exact for n = 1, 2, 4.
EXAMPLE
a(10) = floor((10^5)/3840) = floor(26.0416667) = 26.
a(11) = floor((11^5.5)/10395) = floor(51.3848715) = 51.
MAPLE
A114854 := proc(n)
n^(n/2)/doublefactorial(n) ;
floor(%) ;
end proc:
seq(A114854(n), n=1..35) ; # R. J. Mathar, Jun 23 2014
MATHEMATICA
Table[Floor[n^(n/2)/n!!], {n, 40}] (* Harvey P. Dale, Apr 04 2019 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Feb 20 2006
STATUS
approved