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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 30 |
| 6 | 93 |
| 7 | 267 |
| 8 | 883 |
| 9 | 2804 |
| 10 | 9586 |
| 11 | 32445 |
| 12 | 114178 |
| 13 | 404537 |
| 14 | 1462307 |
| 15 | 5349537 |
| 16 | 19800648 |
| 17 | 74146404 |
| 18 | 280190689 |
| 19 | 1068734524 |
| 20 | 4110516365 |
| 21 | 15922071713 |
| 22 | 62145913561 |
| 23 | 243952955828 |
| 24 | 964002185825 |
| 25 | 3828747254167 |
| 26 | 15290516388596 |
| 27 | 61355753916594 |
| 28 | 247316160801343 |
| 29 | 1001327469687834 |
| 30 | 4069825140933222 |
[1,1,2,4,12,30,93,267,883,2804,9586,32445,114178, 404537,1462307,5349537,19800648,74146404, 280190689,1068734524,4110516365,15922071713, 62145913561,243952955828,964002185825, 3828747254167,15290516388596,61355753916594, 247316160801343,1001327469687834,4069825140933222] |