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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 9 |
| 3 | 48 |
| 4 | 265 |
| 5 | 1512 |
| 6 | 8813 |
| 7 | 52112 |
| 8 | 311427 |
| 9 | 1876290 |
| 10 | 11376893 |
| 11 | 69341868 |
| 12 | 424445996 |
| 13 | 2607388252 |
| 14 | 16066200465 |
| 15 | 99256947520 |
| 16 | 614611513599 |
| 17 | 3813391239444 |
| 18 | 23702418040232 |
| 19 | 147557273500400 |
| 20 | 919907826138042 |
| 21 | 5742264749678028 |
| 22 | 35886019625941713 |
[1,2,9,48,265,1512,8813,52112,311427,1876290, 11376893,69341868,424445996,2607388252, 16066200465,99256947520,614611513599, 3813391239444,23702418040232,147557273500400, 919907826138042,5742264749678028, 35886019625941713] |