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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 27 |
| 5 | 93 |
| 6 | 330 |
| 7 | 1225 |
| 8 | 4748 |
| 9 | 18254 |
| 10 | 72864 |
| 11 | 295766 |
| 12 | 1202739 |
| 13 | 4982093 |
| 14 | 20818757 |
| 15 | 87599870 |
| 16 | 371843504 |
| 17 | 1586274436 |
| 18 | 6819658928 |
| 19 | 29475046107 |
| 20 | 127741159201 |
| 21 | 557407746280 |
| 22 | 2441739857808 |
| 23 | 10717447515735 |
| 24 | 47285645164133 |
| 25 | 209257398094743 |
| 26 | 927976766078263 |
| 27 | 4130130549335293 |
| 28 | 18424601220048862 |
[1,1,3,8,27,93,330,1225,4748,18254,72864,295766, 1202739,4982093,20818757,87599870,371843504, 1586274436,6819658928,29475046107,127741159201, 557407746280,2441739857808,10717447515735, 47285645164133,209257398094743,927976766078263, 4130130549335293,18424601220048862] |