[seqfan] double factorial division
Anchar Koops
anchar.koops at gmail.com
Tue Nov 24 23:13:58 CET 2020
Dear all,
I found an interesting sequence that is not in the OEIS. It is like
factorial but with division instead e.g. input 4 would give 4/ (3/ (2/1)) =
2,666…
Or:
output = n / ((n-1) / ((n-2) / ((n-3) / ... / (3/ (2/1))…)))
I was happy to find it can also be written as:
output = n!! / (n-1)!!
These are the first 10 possible positive integer inputs:
n output |output|
1 1,00 1
2 2,00 2
3 1,50 2
4 2,67 3
5 1,88 2
6 3,20 3
7 2,19 2
8 3,66 4
9 2,46 2
10 4,06 4
As you can see the output oscillates. However, some start inputs e.g.
1,3992863… create a line.
I cannot imagine this has not been found many times before. Is this
sequence worthy?
Thank you very much for your attention.
Anchar
More information about the SeqFan
mailing list