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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 14 |
| 4 | 52 |
| 5 | 209 |
| 6 | 860 |
| 7 | 3611 |
| 8 | 15470 |
| 9 | 67075 |
| 10 | 293936 |
| 11 | 1299135 |
| 12 | 5782369 |
| 13 | 25890073 |
| 14 | 116507143 |
| 15 | 526584341 |
| 16 | 2389109731 |
| 17 | 10875671609 |
| 18 | 49655540621 |
| 19 | 227316843705 |
| 20 | 1043115351009 |
| 21 | 4797021425961 |
| 22 | 22103655032502 |
| 23 | 102032014882075 |
| 24 | 471763934655236 |
| 25 | 2184603451900384 |
| 26 | 10130495327004170 |
| 27 | 47038661457594876 |
[1,1,4,14,52,209,860,3611,15470,67075,293936, 1299135,5782369,25890073,116507143,526584341, 2389109731,10875671609,49655540621,227316843705, 1043115351009,4797021425961,22103655032502, 102032014882075,471763934655236,2184603451900384, 10130495327004170,47038661457594876] |