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| n | a(n) |
|---|---|
| 1 | 16 |
| 2 | 120 |
| 3 | 1360 |
| 4 | 16320 |
| 5 | 209712 |
| 6 | 2795480 |
| 7 | 38347920 |
| 8 | 536862720 |
| 9 | 7635496960 |
| 10 | 109951057896 |
| 11 | 1599289640400 |
| 12 | 23456246655680 |
| 13 | 346430740566960 |
| 14 | 5146970983535160 |
| 15 | 76861433640386288 |
| 16 | 1152921504338411520 |
| 17 | 17361641481138401520 |
| 18 | 262353693488939386880 |
| 19 | 3976729669784964390480 |
[16,120,1360,16320,209712,2795480,38347920, 536862720,7635496960,109951057896,1599289640400, 23456246655680,346430740566960,5146970983535160, 76861433640386288,1152921504338411520, 17361641481138401520,262353693488939386880, 3976729669784964390480] |