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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 17 |
| 3 | 115 |
| 4 | 863 |
| 5 | 6903 |
| 6 | 57687 |
| 7 | 497683 |
| 8 | 4398980 |
| 9 | 39630305 |
| 10 | 362562226 |
| 11 | 3359252039 |
| 12 | 31457036708 |
| 13 | 297247495745 |
| 14 | 2830725974514 |
| 15 | 27140465365203 |
| 16 | 261768686779800 |
| 17 | 2538061348959000 |
| 18 | 24724191398850125 |
| 19 | 241862002342417585 |
| 20 | 2374978445599884762 |
[1,3,17,115,863,6903,57687,497683,4398980, 39630305,362562226,3359252039,31457036708, 297247495745,2830725974514,27140465365203, 261768686779800,2538061348959000, 24724191398850125,241862002342417585, 2374978445599884762] |