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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 10 |
| 5 | 40 |
| 6 | 153 |
| 7 | 921 |
| 8 | 5144 |
| 9 | 30717 |
| 10 | 230748 |
| 11 | 1766056 |
| 12 | 14052445 |
| 13 | 116580521 |
| 14 | 897876519 |
| 15 | 7657321097 |
| 16 | 75743979608 |
| 17 | 788733735080 |
| 18 | 7569825650083 |
| 19 | 75242386295617 |
| 20 | 831978453306391 |
| 21 | 9444103049405370 |
| 22 | 120064355466770831 |
| 23 | 1579842230380587833 |
[1,0,1,3,10,40,153,921,5144,30717,230748,1766056, 14052445,116580521,897876519,7657321097, 75743979608,788733735080,7569825650083, 75242386295617,831978453306391,9444103049405370, 120064355466770831,1579842230380587833] |