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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 18 |
| 3 | 164 |
| 4 | 1810 |
| 5 | 21252 |
| 6 | 263844 |
| 7 | 3395016 |
| 8 | 44916498 |
| 9 | 607041380 |
| 10 | 8345319268 |
| 11 | 116335834056 |
| 12 | 1640651321764 |
| 13 | 23365271704712 |
| 14 | 335556407724360 |
| 15 | 4854133484555664 |
| 16 | 70666388112940818 |
| 17 | 1034529673001901732 |
[1,2,18,164,1810,21252,263844,3395016,44916498, 607041380,8345319268,116335834056,1640651321764, 23365271704712,335556407724360,4854133484555664, 70666388112940818,1034529673001901732] |