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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 42 |
| 6 | 132 |
| 7 | 1430 |
| 8 | 4862 |
| 9 | 58786 |
| 10 | 2674440 |
| 11 | 9694845 |
| 12 | 477638700 |
| 13 | 6564120420 |
| 14 | 24466267020 |
| 15 | 343059613650 |
| 16 | 18367353072152 |
| 17 | 1002242216651368 |
| 18 | 3814986502092304 |
| 19 | 212336130412243110 |
| 20 | 3116285494907301262 |
[1,2,5,42,132,1430,4862,58786,2674440,9694845, 477638700,6564120420,24466267020,343059613650, 18367353072152,1002242216651368,3814986502092304, 212336130412243110,3116285494907301262] |