login
The OEIS is supported by
the many generous donors to the OEIS Foundation
.
Hints
(Greetings from
The On-Line Encyclopedia of Integer Sequences
!)
A018398
as a simple table
n
a(n)
1
1
2
3
3
9
4
37
5
111
6
333
[1,3,9,37,111,333]
