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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 21 |
| 6 | 59 |
| 7 | 162 |
| 8 | 483 |
| 9 | 1453 |
| 10 | 4492 |
| 11 | 14048 |
| 12 | 44616 |
| 13 | 142936 |
| 14 | 462380 |
| 15 | 1506534 |
| 16 | 4941955 |
| 17 | 16303783 |
| 18 | 54066560 |
| 19 | 180111432 |
| 20 | 602481589 |
| 21 | 2022797529 |
| 22 | 6814336663 |
| 23 | 23026359634 |
| 24 | 78027238290 |
| 25 | 265085903996 |
| 26 | 902733374480 |
| 27 | 3080967048004 |
| 28 | 10536594982790 |
| 29 | 36102498293396 |
| 30 | 123920278459564 |
[1,2,4,9,21,59,162,483,1453,4492,14048,44616, 142936,462380,1506534,4941955,16303783,54066560, 180111432,602481589,2022797529,6814336663, 23026359634,78027238290,265085903996,902733374480, 3080967048004,10536594982790,36102498293396, 123920278459564] |