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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 9 |
| 3 | 17 |
| 4 | 72 |
| 5 | 209 |
| 6 | 711 |
| 7 | 2250 |
| 8 | 7357 |
| 9 | 23693 |
| 10 | 76848 |
| 11 | 248413 |
| 12 | 804307 |
| 13 | 2602122 |
| 14 | 8421705 |
| 15 | 27251521 |
| 16 | 88190472 |
| 17 | 285386041 |
| 18 | 923535567 |
| 19 | 2988612714 |
| 20 | 9671371877 |
| 21 | 31297187845 |
| 22 | 101279874144 |
| 23 | 327748481957 |
| 24 | 1060616489147 |
| 25 | 3432226859754 |
[0,9,17,72,209,711,2250,7357,23693,76848,248413, 804307,2602122,8421705,27251521,88190472, 285386041,923535567,2988612714,9671371877, 31297187845,101279874144,327748481957, 1060616489147,3432226859754] |