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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 88 |
| 4 | 1148 |
| 5 | 20088 |
| 6 | 442896 |
| 7 | 11802096 |
| 8 | 369132256 |
| 9 | 13261156416 |
| 10 | 538227938880 |
| 11 | 24359100451200 |
| 12 | 1216403663398656 |
| 13 | 66440221207025664 |
| 14 | 3940468338389603328 |
| 15 | 252190997066643909120 |
| 16 | 17324237625466992906240 |
| 17 | 1271459220768570290626560 |
| 18 | 99289436336361780797288448 |
[1,2,10,88,1148,20088,442896,11802096,369132256, 13261156416,538227938880,24359100451200, 1216403663398656,66440221207025664, 3940468338389603328,252190997066643909120, 17324237625466992906240,1271459220768570290626560, 99289436336361780797288448] |