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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 9 |
| 4 | 24 |
| 5 | 126 |
| 6 | 972 |
| 7 | 7056 |
| 8 | 46656 |
| 9 | 297432 |
| 10 | 1806624 |
| 11 | 10478160 |
| 12 | 60466176 |
| 13 | 356638464 |
| 14 | 2142770112 |
| 15 | 12958657344 |
| 16 | 78328332288 |
| 17 | 471877757568 |
| 18 | 2832129868032 |
| 19 | 16960580969472 |
| 20 | 101559956668416 |
| 21 | 608764662139392 |
| 22 | 3652649829734400 |
| 23 | 21926486787222528 |
| 24 | 131621703842267136 |
[0,2,9,24,126,972,7056,46656,297432,1806624, 10478160,60466176,356638464,2142770112, 12958657344,78328332288,471877757568, 2832129868032,16960580969472,101559956668416, 608764662139392,3652649829734400, 21926486787222528,131621703842267136] |