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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 6 |
| 5 | 45 |
| 6 | 315 |
| 7 | 2205 |
| 8 | 15624 |
| 9 | 111888 |
| 10 | 807840 |
| 11 | 5868720 |
| 12 | 42799680 |
| 13 | 312504192 |
| 14 | 2278418688 |
| 15 | 16549827840 |
| 16 | 119567831040 |
| 17 | 858293084160 |
| 18 | 6118081708032 |
| 19 | 43298650386432 |
| 20 | 304260332175360 |
| 21 | 2123395686236160 |
| 22 | 14722247331348480 |
| 23 | 101446590051975168 |
| 24 | 695007859780878336 |
| 25 | 4735844958575001600 |
[1,6,45,315,2205,15624,111888,807840,5868720, 42799680,312504192,2278418688,16549827840, 119567831040,858293084160,6118081708032, 43298650386432,304260332175360,2123395686236160, 14722247331348480,101446590051975168, 695007859780878336,4735844958575001600] |