| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 5 |
| 4 | 8 |
| 5 | 45 |
| 6 | 128 |
| 7 | 505 |
| 8 | 1680 |
| 9 | 6089 |
| 10 | 21120 |
| 11 | 74909 |
| 12 | 262680 |
| 13 | 926485 |
| 14 | 3258112 |
| 15 | 11474865 |
| 16 | 40382752 |
| 17 | 142171985 |
| 18 | 500432640 |
| 19 | 1761656821 |
| 20 | 6201182760 |
| 21 | 21829269181 |
| 22 | 76841888640 |
| 23 | 270495370025 |
| 24 | 952182350768 |
| 25 | 3351823875225 |
| 26 | 11798909226368 |
[1,0,5,8,45,128,505,1680,6089,21120,74909,262680, 926485,3258112,11474865,40382752,142171985, 500432640,1761656821,6201182760,21829269181, 76841888640,270495370025,952182350768, 3351823875225,11798909226368] |