login
The OEIS is supported by
the many generous donors to the OEIS Foundation
.
Hints
(Greetings from
The On-Line Encyclopedia of Integer Sequences
!)
A002811
as a simple table
n
a(n)
1
1
2
5
3
23
4
1681
5
257543
6
67637281
7
27138236663
8
15442193173681
[1,5,23,1681,257543,67637281,27138236663, 15442193173681]