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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 9 |
| 3 | 50 |
| 4 | 254 |
| 5 | 1287 |
| 6 | 6630 |
| 7 | 34846 |
| 8 | 186714 |
| 9 | 1018095 |
| 10 | 5638035 |
| 11 | 31651992 |
| 12 | 179850344 |
| 13 | 1032901028 |
| 14 | 5988670002 |
| 15 | 35017696806 |
| 16 | 206326044386 |
| 17 | 1224068679855 |
| 18 | 7307391855855 |
| 19 | 43871253636210 |
| 20 | 264755875041630 |
| 21 | 1605357997312335 |
| 22 | 9776732655285960 |
| 23 | 59781214452500424 |
| 24 | 366905787075963864 |
[1,9,50,254,1287,6630,34846,186714,1018095, 5638035,31651992,179850344,1032901028,5988670002, 35017696806,206326044386,1224068679855, 7307391855855,43871253636210,264755875041630, 1605357997312335,9776732655285960, 59781214452500424,366905787075963864] |