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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 1 |
| 3 | 4 |
| 4 | 17 |
| 5 | 76 |
| 6 | 354 |
| 7 | 1704 |
| 8 | 8421 |
| 9 | 42508 |
| 10 | 218318 |
| 11 | 1137400 |
| 12 | 5996938 |
| 13 | 31940792 |
| 14 | 171605956 |
| 15 | 928931280 |
| 16 | 5061593709 |
| 17 | 27739833228 |
| 18 | 152809506582 |
| 19 | 845646470616 |
| 20 | 4699126915422 |
| 21 | 26209721959656 |
| 22 | 146681521121244 |
| 23 | 823429928805936 |
| 24 | 4635568494271458 |
[2,1,4,17,76,354,1704,8421,42508,218318,1137400, 5996938,31940792,171605956,928931280,5061593709, 27739833228,152809506582,845646470616, 4699126915422,26209721959656,146681521121244, 823429928805936,4635568494271458] |