The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 18 |
| 5 | 305 |
| 6 | 5595 |
| 7 | 113974 |
| 8 | 2581964 |
| 9 | 64727522 |
| 10 | 1783995060 |
| 11 | 53705023251 |
| 12 | 1755078270264 |
| 13 | 61920105083187 |
| 14 | 2346728722199680 |
| 15 | 95117694573257784 |
| 16 | 4106779625155078528 |
| 17 | 188206877039146217476 |
| 18 | 9125798298446360109312 |
| 19 | 466820173490890114763781 |
| 20 | 25126459591455539907002880 |
[1,18,305,5595,113974,2581964,64727522,1783995060, 53705023251,1755078270264,61920105083187, 2346728722199680,95117694573257784, 4106779625155078528,188206877039146217476, 9125798298446360109312,466820173490890114763781, 25126459591455539907002880] |