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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 96 |
| 3 | 508 |
| 4 | 3088 |
| 5 | 18440 |
| 6 | 111900 |
| 7 | 675600 |
| 8 | 4094240 |
| 9 | 24794560 |
| 10 | 150165020 |
| 11 | 909361668 |
| 12 | 5507667148 |
| 13 | 33356744732 |
| 14 | 202019640344 |
| 15 | 1223500857956 |
| 16 | 7410005643024 |
| 17 | 44877800876060 |
| 18 | 271796556988084 |
| 19 | 1646101595999968 |
| 20 | 9969411699754184 |
[6,96,508,3088,18440,111900,675600,4094240, 24794560,150165020,909361668,5507667148, 33356744732,202019640344,1223500857956, 7410005643024,44877800876060,271796556988084, 1646101595999968,9969411699754184] |