1,2
This is to double factorial A006882 as A055775 "Floor(n^n/n!)" is to factorial. This sequence is a weak first approximation of a double factorial analogue to Stirling's approximation to factorial. Note that a(n) is exact for n = 1, 2, 3, 4, 6.
a(n) = Floor[n^n/n!! ]. a(n) = Floor[A000312(n)/A006882(n)].
a(10) = Floor[(10^10)/3840] = Floor[2604166.67] = 2604166.
Cf. A000312, A006882, A055775.
Sequence in context: A150920 A013501 A179230 * A110376 A036505 A056916
Adjacent sequences: A114850 A114851 A114852 * A114854 A114855 A114856
easy,nonn
Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 20 2006
