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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 14 |
| 3 | 72 |
| 4 | 343 |
| 5 | 1920 |
| 6 | 11444 |
| 7 | 68112 |
| 8 | 405019 |
| 9 | 2422502 |
| 10 | 14527358 |
| 11 | 87130296 |
| 12 | 522558079 |
| 13 | 3134839248 |
| 14 | 18808467356 |
| 15 | 112848487824 |
| 16 | 677075548723 |
| 17 | 4062417593558 |
| 18 | 24374464952438 |
| 19 | 146246626666296 |
| 20 | 877478675492551 |
| 21 | 5264869525163232 |
[2,14,72,343,1920,11444,68112,405019,2422502, 14527358,87130296,522558079,3134839248, 18808467356,112848487824,677075548723, 4062417593558,24374464952438,146246626666296, 877478675492551,5264869525163232] |