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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 6 |
| 4 | 40 |
| 5 | 120 |
| 6 | 512 |
| 7 | 2016 |
| 8 | 8320 |
| 9 | 32640 |
| 10 | 131072 |
| 11 | 523776 |
| 12 | 2099200 |
| 13 | 8386560 |
| 14 | 33554432 |
| 15 | 134209536 |
| 16 | 536903680 |
| 17 | 2147450880 |
| 18 | 8589934592 |
| 19 | 34359607296 |
| 20 | 137439477760 |
| 21 | 549755289600 |
| 22 | 2199023255552 |
| 23 | 8796090925056 |
| 24 | 35184380477440 |
| 25 | 140737479966720 |
| 26 | 562949953421312 |
[1,0,2,6,40,120,512,2016,8320,32640,131072,523776, 2099200,8386560,33554432,134209536,536903680, 2147450880,8589934592,34359607296,137439477760, 549755289600,2199023255552,8796090925056, 35184380477440,140737479966720,562949953421312] |