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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 26 |
| 5 | 67 |
| 6 | 216 |
| 7 | 555 |
| 8 | 1704 |
| 9 | 4538 |
| 10 | 13320 |
| 11 | 35376 |
| 12 | 103863 |
| 13 | 273792 |
| 14 | 783694 |
| 15 | 2101835 |
| 16 | 5905044 |
| 17 | 15745360 |
| 18 | 44132278 |
| 19 | 117267422 |
| 20 | 325136638 |
| 21 | 868034994 |
| 22 | 2379074541 |
| 23 | 6337238658 |
| 24 | 17347580484 |
| 25 | 46039358056 |
| 26 | 125056019725 |
| 27 | 332678989816 |
| 28 | 898361151760 |
| 29 | 2382959919616 |
[1,1,3,8,26,67,216,555,1704,4538,13320,35376, 103863,273792,783694,2101835,5905044,15745360, 44132278,117267422,325136638,868034994,2379074541, 6337238658,17347580484,46039358056,125056019725, 332678989816,898361151760,2382959919616] |