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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 27 |
| 5 | 104 |
| 6 | 436 |
| 7 | 1930 |
| 8 | 8871 |
| 9 | 41916 |
| 10 | 202300 |
| 11 | 992942 |
| 12 | 4940912 |
| 13 | 24867870 |
| 14 | 126371426 |
| 15 | 647494746 |
| 16 | 3341341155 |
| 17 | 17350565376 |
| 18 | 90593056624 |
| 19 | 475333630402 |
| 20 | 2504959102224 |
| 21 | 13252904123786 |
| 22 | 70366654738470 |
| 23 | 374824160997086 |
[1,1,3,8,27,104,436,1930,8871,41916,202300,992942, 4940912,24867870,126371426,647494746,3341341155, 17350565376,90593056624,475333630402, 2504959102224,13252904123786,70366654738470, 374824160997086] |