The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 14 |
| 3 | 14 |
| 4 | 126 |
| 5 | 252 |
| 6 | 1050 |
| 7 | 2772 |
| 8 | 8778 |
| 9 | 24948 |
| 10 | 72072 |
| 11 | 204204 |
| 12 | 570570 |
| 13 | 1585584 |
| 14 | 4351776 |
| 15 | 11879868 |
| 16 | 32162130 |
| 17 | 86582496 |
| 18 | 231703472 |
| 19 | 616900284 |
| 20 | 1634721088 |
| 21 | 4312944064 |
| 22 | 11333823228 |
| 23 | 29673291648 |
| 24 | 77423101938 |
| 25 | 201367680696 |
| 26 | 522180220044 |
| 27 | 1350350044316 |
| 28 | 3482928560880 |
[1,0,14,14,126,252,1050,2772,8778,24948,72072, 204204,570570,1585584,4351776,11879868,32162130, 86582496,231703472,616900284,1634721088, 4312944064,11333823228,29673291648,77423101938, 201367680696,522180220044,1350350044316, 3482928560880] |