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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 18 |
| 3 | 154 |
| 4 | 1689 |
| 5 | 22518 |
| 6 | 353211 |
| 7 | 6373053 |
| 8 | 130079286 |
| 9 | 2964644430 |
| 10 | 74663152896 |
| 11 | 2060033160771 |
| 12 | 61821589542329 |
| 13 | 2005535153907369 |
| 14 | 69957741972993120 |
| 15 | 2611812581931916545 |
| 16 | 103938147849788867430 |
| 17 | 4392991505873072541159 |
[1,3,18,154,1689,22518,353211,6373053,130079286, 2964644430,74663152896,2060033160771, 61821589542329,2005535153907369,69957741972993120, 2611812581931916545,103938147849788867430, 4392991505873072541159] |