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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 14 |
| 3 | 72 |
| 4 | 388 |
| 5 | 2150 |
| 6 | 12134 |
| 7 | 69370 |
| 8 | 400398 |
| 9 | 2328162 |
| 10 | 13616892 |
| 11 | 80022612 |
| 12 | 472133638 |
| 13 | 2794893246 |
| 14 | 16592160944 |
| 15 | 98743919468 |
| 16 | 588913687966 |
| 17 | 3518968100982 |
| 18 | 21062444053040 |
| 19 | 126256612255260 |
| 20 | 757853797478188 |
[1,3,14,72,388,2150,12134,69370,400398,2328162, 13616892,80022612,472133638,2794893246, 16592160944,98743919468,588913687966, 3518968100982,21062444053040,126256612255260, 757853797478188] |