The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 72 |
| 6 | 1010 |
| 7 | 36302 |
| 8 | 3501500 |
| 9 | 984382830 |
| 10 | 820391106394 |
| 11 | 2231837962830894 |
| 12 | 19443994569352596154 |
| 13 | 611248544067759392038426 |
| 14 | 65374059149370152526265388842 |
| 15 | 27613396368509694864033710442373202 |
[1,2,4,12,72,1010,36302,3501500,984382830, 820391106394,2231837962830894, 19443994569352596154,611248544067759392038426, 65374059149370152526265388842, 27613396368509694864033710442373202] |