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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 18 |
| 3 | 56 |
| 4 | 223 |
| 5 | 849 |
| 6 | 3387 |
| 7 | 13075 |
| 8 | 51006 |
| 9 | 199243 |
| 10 | 777845 |
| 11 | 3035261 |
| 12 | 11848853 |
| 13 | 46252538 |
| 14 | 180542983 |
| 15 | 704739373 |
| 16 | 2750937235 |
| 17 | 10738195965 |
| 18 | 41916200522 |
| 19 | 163618636603 |
| 20 | 638680511133 |
| 21 | 2493070208921 |
| 22 | 9731625088447 |
| 23 | 37987108531520 |
[1,18,56,223,849,3387,13075,51006,199243,777845, 3035261,11848853,46252538,180542983,704739373, 2750937235,10738195965,41916200522,163618636603, 638680511133,2493070208921,9731625088447, 37987108531520] |