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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 8 |
| 4 | 52 |
| 5 | 247 |
| 6 | 1416 |
| 7 | 6056 |
| 8 | 33731 |
| 9 | 139016 |
| 10 | 770116 |
| 11 | 3121259 |
| 12 | 17335095 |
| 13 | 69642995 |
| 14 | 388958218 |
| 15 | 1554558921 |
| 16 | 8740670953 |
| 17 | 34818606079 |
| 18 | 197136480944 |
| 19 | 783522002716 |
| 20 | 4466326137854 |
| 21 | 17722654061673 |
| 22 | 101674164224552 |
| 23 | 402960855102206 |
| 24 | 2325563749837462 |
| 25 | 9208279020729297 |
| 26 | 53433859702165884 |
[1,8,52,247,1416,6056,33731,139016,770116,3121259, 17335095,69642995,388958218,1554558921,8740670953, 34818606079,197136480944,783522002716, 4466326137854,17722654061673,101674164224552, 402960855102206,2325563749837462,9208279020729297, 53433859702165884] |