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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 16 |
| 3 | 84 |
| 4 | 440 |
| 5 | 2304 |
| 6 | 12064 |
| 7 | 63168 |
| 8 | 330752 |
| 9 | 1731840 |
| 10 | 9068032 |
| 11 | 47480832 |
| 12 | 248612864 |
| 13 | 1301753856 |
| 14 | 6816071680 |
| 15 | 35689414656 |
| 16 | 186872201216 |
| 17 | 978475548672 |
| 18 | 5123364487168 |
| 19 | 26826284728320 |
| 20 | 140464250421248 |
| 21 | 735480363614208 |
| 22 | 3851025180000256 |
| 23 | 20164229625544704 |
| 24 | 105581277033267200 |
[3,16,84,440,2304,12064,63168,330752,1731840, 9068032,47480832,248612864,1301753856,6816071680, 35689414656,186872201216,978475548672, 5123364487168,26826284728320,140464250421248, 735480363614208,3851025180000256, 20164229625544704,105581277033267200] |