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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 30 |
| 5 | 126 |
| 6 | 648 |
| 7 | 3591 |
| 8 | 19953 |
| 9 | 110079 |
| 10 | 610500 |
| 11 | 3440493 |
| 12 | 19742616 |
| 13 | 114918138 |
| 14 | 675417474 |
| 15 | 3996992547 |
| 16 | 23791052862 |
| 17 | 142393544757 |
| 18 | 856746349992 |
| 19 | 5179722791274 |
| 20 | 31449875426622 |
| 21 | 191678795532801 |
| 22 | 1172198278949454 |
| 23 | 7190652243631437 |
| 24 | 44235165115911312 |
| 25 | 272837082264574914 |
[1,3,9,30,126,648,3591,19953,110079,610500, 3440493,19742616,114918138,675417474,3996992547, 23791052862,142393544757,856746349992, 5179722791274,31449875426622,191678795532801, 1172198278949454,7190652243631437, 44235165115911312,272837082264574914] |