login
The OEIS is supported by
the many generous donors to the OEIS Foundation
.
Hints
(Greetings from
The On-Line Encyclopedia of Integer Sequences
!)
A007020
as a simple table
n
a(n)
3
1
4
1
5
1
6
2
7
5
8
13
9
33
10
85
11
199
12
445
13
947
14
1909
15
3713
16
7006
17
12765
18
22764
19
39540
[1,1,1,2,5,13,33,85,199,445,947,1909,3713,7006, 12765,22764,39540]