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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 5 |
| 5 | 686 |
| 6 | 13942 |
| 7 | 455988 |
| 8 | 13617853 |
| 9 | 454222894 |
| 10 | 18323165948 |
| 11 | 802161109047 |
| 12 | 42149084452070 |
| 13 | 2481730049781672 |
| 14 | 157265294178424356 |
| 15 | 10977302934685469078 |
| 16 | 812821237985857557677 |
| 17 | 64539935903231450294134 |
| 18 | 5504599828399250884049308 |
[1,1,1,4,5,686,13942,455988,13617853,454222894, 18323165948,802161109047,42149084452070, 2481730049781672,157265294178424356, 10977302934685469078,812821237985857557677, 64539935903231450294134,5504599828399250884049308] |