| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 119 |
| 6 | 711 |
| 7 | 4981 |
| 8 | 39903 |
| 9 | 359537 |
| 10 | 3598696 |
| 11 | 39615626 |
| 12 | 475687487 |
| 13 | 6187239476 |
| 14 | 86661001741 |
| 15 | 1300430722200 |
| 16 | 20814114415224 |
| 17 | 353948328666101 |
| 18 | 6372804626194310 |
| 19 | 121112786592293964 |
| 20 | 2422786846761133394 |
| 21 | 50888617325509644404 |
| 22 | 1119751494628234263303 |
[0,1,2,6,24,119,711,4981,39903,359537,3598696, 39615626,475687487,6187239476,86661001741, 1300430722200,20814114415224,353948328666101, 6372804626194310,121112786592293964, 2422786846761133394,50888617325509644404, 1119751494628234263303] |