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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 8 |
| 3 | 20 |
| 4 | 240 |
| 5 | 696 |
| 6 | 280 |
| 7 | 5408 |
| 8 | 21216 |
| 9 | 3940 |
| 10 | 57072 |
| 11 | 275568 |
| 12 | 277200 |
| 13 | 1873816 |
| 14 | 2585024 |
| 15 | 4680600 |
| 16 | 54616512 |
| 17 | 81841608 |
| 18 | 10976840 |
| 19 | 530008720 |
| 20 | 1919331360 |
| 21 | 1235646880 |
| 22 | 4474673184 |
| 23 | 21605633376 |
| 24 | 28253665440 |
| 25 | 162655527004 |
| 26 | 177341693872 |
| 27 | 30581480180 |
| 28 | 2953208968320 |
[1,4,8,20,240,696,280,5408,21216,3940,57072, 275568,277200,1873816,2585024,4680600,54616512, 81841608,10976840,530008720,1919331360,1235646880, 4474673184,21605633376,28253665440,162655527004, 177341693872,30581480180,2953208968320] |