n | a(n) |
---|---|
1 | 4 |
2 | 15 |
3 | 53 |
4 | 138 |
5 | 483 |
6 | 1678 |
7 | 5634 |
8 | 18915 |
9 | 62325 |
10 | 204315 |
11 | 683210 |
12 | 2277118 |
13 | 7559559 |
14 | 25132611 |
15 | 83206528 |
16 | 274465209 |
17 | 907716605 |
18 | 3004041236 |
19 | 9908081432 |
[4,15,53,138,483,1678,5634,18915,62325,204315, 683210,2277118,7559559,25132611,83206528, 274465209,907716605,3004041236,9908081432] |