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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 57 |
| 5 | 304 |
| 6 | 1778 |
| 7 | 11329 |
| 8 | 79293 |
| 9 | 626614 |
| 10 | 5911340 |
| 11 | 72622218 |
| 12 | 1271963335 |
| 13 | 33126504453 |
| 14 | 1266054182987 |
| 15 | 69124699233986 |
| 16 | 5301840148829273 |
| 17 | 566953161970598904 |
| 18 | 84240794164243627206 |
| 19 | 17363983133374688843928 |
[1,1,3,12,57,304,1778,11329,79293,626614,5911340, 72622218,1271963335,33126504453,1266054182987, 69124699233986,5301840148829273, 566953161970598904,84240794164243627206, 17363983133374688843928] |