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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 16 |
| 5 | 46 |
| 6 | 142 |
| 7 | 496 |
| 8 | 1888 |
| 9 | 7538 |
| 10 | 31291 |
| 11 | 135739 |
| 12 | 617461 |
| 13 | 2939215 |
| 14 | 14575027 |
| 15 | 75014471 |
| 16 | 399901294 |
| 17 | 2205630124 |
| 18 | 12572140372 |
| 19 | 73961880118 |
| 20 | 448447331338 |
| 21 | 2798640572516 |
| 22 | 17956583819425 |
| 23 | 118336081817953 |
| 24 | 800278211629795 |
| 25 | 5549154792085813 |
| 26 | 39420390891260821 |
[1,1,1,5,16,46,142,496,1888,7538,31291,135739, 617461,2939215,14575027,75014471,399901294, 2205630124,12572140372,73961880118,448447331338, 2798640572516,17956583819425,118336081817953, 800278211629795,5549154792085813, 39420390891260821] |