1,4
This sequence is a second approximation of a double factorial analogue to Stirling's approximation to factorial. Note that a(n) is exact for n = 1, 2, 4.
Table of n, a(n) for n=1..26.
a(n) = Floor[n^(n/2)/n!! ]. a(n) = Floor[Sqrt(A000312(n))/A006882(n)].
a(10) = Floor[(10^5)/3840] = Floor[26.0416667] = 26.
a(11) = Floor[(11^5.5)/10395] = Floor[51.3848715] = 51.
Cf. A000312, A006882, A055775.
Sequence in context: A037171 A186417 A207644 * A127279 A050727 A102951
Adjacent sequences: A114851 A114852 A114853 * A114855 A114856 A114857
easy,nonn
Jonathan Vos Post, Feb 20 2006
approved
