login
The OEIS is supported by
the many generous donors to the OEIS Foundation
.
Hints
(Greetings from
The On-Line Encyclopedia of Integer Sequences
!)
A305857
as a simple table
n
a(n)
0
1
1
2
2
3
3
6
4
15
5
87
6
3528
7
47174113
[1,2,3,6,15,87,3528,47174113]