login
The OEIS is supported by
the many generous donors to the OEIS Foundation
.
Hints
(Greetings from
The On-Line Encyclopedia of Integer Sequences
!)
A006406
as a simple table
n
a(n)
3
1
4
1
5
2
6
4
7
9
8
24
9
81
10
274
11
1071
12
4357
13
18416
14
80040
15
356109
16
1610910
17
7399114
[1,1,2,4,9,24,81,274,1071,4357,18416,80040,356109, 1610910,7399114]