| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 56 |
| 4 | 330 |
| 5 | 2002 |
| 6 | 12376 |
| 7 | 77520 |
| 8 | 490314 |
| 9 | 3124550 |
| 10 | 20030010 |
| 11 | 129024480 |
| 12 | 834451800 |
| 13 | 5414950296 |
| 14 | 35240152720 |
| 15 | 229911617056 |
| 16 | 1503232609098 |
| 17 | 9847379391150 |
| 18 | 64617565719070 |
| 19 | 424655979547800 |
| 20 | 2794563003870330 |
| 21 | 18412956934908690 |
| 22 | 121455445321173600 |
[1,2,10,56,330,2002,12376,77520,490314,3124550, 20030010,129024480,834451800,5414950296, 35240152720,229911617056,1503232609098, 9847379391150,64617565719070,424655979547800, 2794563003870330,18412956934908690, 121455445321173600] |