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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 16 |
| 4 | 55 |
| 5 | 355 |
| 6 | 1888 |
| 7 | 9829 |
| 8 | 57145 |
| 9 | 294064 |
| 10 | 1683055 |
| 11 | 8893147 |
| 12 | 49635520 |
| 13 | 267601933 |
| 14 | 1472118817 |
| 15 | 8012384080 |
| 16 | 43823300455 |
| 17 | 239288418067 |
| 18 | 1306681029664 |
| 19 | 7139564615413 |
| 20 | 38980858167625 |
| 21 | 212971742938096 |
| 22 | 1162967620577311 |
[1,1,1,16,55,355,1888,9829,57145,294064,1683055, 8893147,49635520,267601933,1472118817,8012384080, 43823300455,239288418067,1306681029664, 7139564615413,38980858167625,212971742938096, 1162967620577311] |