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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 18 |
| 5 | 171 |
| 6 | 2283 |
| 7 | 39942 |
| 8 | 874944 |
| 9 | 23243829 |
| 10 | 731486637 |
| 11 | 26782956144 |
| 12 | 1124838704976 |
| 13 | 53567894139165 |
| 14 | 2865318598843281 |
| 15 | 170774893724336223 |
| 16 | 11264050942430761881 |
| 17 | 817374450539598433587 |
| 18 | 64917115563124199691834 |
[1,1,3,18,171,2283,39942,874944,23243829, 731486637,26782956144,1124838704976, 53567894139165,2865318598843281, 170774893724336223,11264050942430761881, 817374450539598433587,64917115563124199691834] |