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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 11 |
| 3 | 44 |
| 4 | 186 |
| 5 | 819 |
| 6 | 3725 |
| 7 | 17402 |
| 8 | 83156 |
| 9 | 405116 |
| 10 | 2006696 |
| 11 | 10083578 |
| 12 | 51303146 |
| 13 | 263851841 |
| 14 | 1369807435 |
| 15 | 7170160392 |
| 16 | 37803475750 |
| 17 | 200584271466 |
| 18 | 1070306614530 |
| 19 | 5739790997296 |
| 20 | 30919312935436 |
| 21 | 167228980869678 |
| 22 | 907759276349466 |
[1,3,11,44,186,819,3725,17402,83156,405116, 2006696,10083578,51303146,263851841,1369807435, 7170160392,37803475750,200584271466,1070306614530, 5739790997296,30919312935436,167228980869678, 907759276349466] |