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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 8 |
| 3 | 18 |
| 4 | 45 |
| 5 | 125 |
| 6 | 320 |
| 7 | 832 |
| 8 | 2197 |
| 9 | 5733 |
| 10 | 14994 |
| 11 | 39304 |
| 12 | 102850 |
| 13 | 269225 |
| 14 | 704969 |
| 15 | 1845504 |
| 16 | 4831488 |
| 17 | 12649337 |
| 18 | 33116057 |
| 19 | 86698690 |
| 20 | 226981000 |
| 21 | 594243090 |
| 22 | 1555747893 |
| 23 | 4073003173 |
| 24 | 10663258432 |
| 25 | 27916771136 |
| 26 | 73087061741 |
| 27 | 191344405725 |
[2,8,18,45,125,320,832,2197,5733,14994,39304, 102850,269225,704969,1845504,4831488,12649337, 33116057,86698690,226981000,594243090,1555747893, 4073003173,10663258432,27916771136,73087061741, 191344405725] |