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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 116 |
| 5 | 630 |
| 6 | 24054 |
| 7 | 273000 |
| 8 | 11105072 |
| 9 | 207213552 |
| 10 | 9175467960 |
| 11 | 245785969440 |
| 12 | 11954556125544 |
| 13 | 421832039016960 |
| 14 | 22609694372667024 |
| 15 | 991695134898861120 |
| 16 | 58565049582761702400 |
| 17 | 3065736317041568378880 |
| 18 | 199024242549235933723200 |
[1,0,2,3,116,630,24054,273000,11105072,207213552, 9175467960,245785969440,11954556125544, 421832039016960,22609694372667024, 991695134898861120,58565049582761702400, 3065736317041568378880,199024242549235933723200] |