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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 52 |
| 3 | 530 |
| 4 | 5919 |
| 5 | 70098 |
| 6 | 864784 |
| 7 | 10994490 |
| 8 | 143042020 |
| 9 | 1895316632 |
| 10 | 25487708844 |
| 11 | 346976558318 |
| 12 | 4772478619146 |
| 13 | 66222166440780 |
| 14 | 925880434336320 |
| 15 | 13030945427540170 |
| 16 | 184467676431001644 |
| 17 | 2624828100099166536 |
| 18 | 37521220349342729680 |
| 19 | 538573138719587026440 |
[1,6,52,530,5919,70098,864784,10994490,143042020, 1895316632,25487708844,346976558318,4772478619146, 66222166440780,925880434336320,13030945427540170, 184467676431001644,2624828100099166536, 37521220349342729680,538573138719587026440] |