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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 51 |
| 6 | 196 |
| 7 | 854 |
| 8 | 3830 |
| 9 | 17997 |
| 10 | 86419 |
| 11 | 422004 |
| 12 | 2079260 |
| 13 | 10306751 |
| 14 | 51263086 |
| 15 | 255514299 |
| 16 | 1275160060 |
| 17 | 6368612301 |
| 18 | 31821454413 |
| 19 | 159042661904 |
| 20 | 795019250650 |
| 21 | 3974515029793 |
| 22 | 19870830290476 |
| 23 | 99348921288654 |
| 24 | 496728909635860 |
| 25 | 2483597478617750 |
| 26 | 12417846151236799 |
[1,1,4,13,51,196,854,3830,17997,86419,422004, 2079260,10306751,51263086,255514299,1275160060, 6368612301,31821454413,159042661904,795019250650, 3974515029793,19870830290476,99348921288654, 496728909635860,2483597478617750, 12417846151236799] |