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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 26 |
| 4 | 398 |
| 5 | 9724 |
| 6 | 344236 |
| 7 | 16663968 |
| 8 | 1056631824 |
| 9 | 84962783664 |
| 10 | 8446120969104 |
| 11 | 1016998946575776 |
| 12 | 145848462866589600 |
| 13 | 24562489788256472064 |
| 14 | 4799789988678066147840 |
| 15 | 1077128972416478325901824 |
| 16 | 275111625956753684599202304 |
[1,1,3,26,398,9724,344236,16663968,1056631824, 84962783664,8446120969104,1016998946575776, 145848462866589600,24562489788256472064, 4799789988678066147840,1077128972416478325901824, 275111625956753684599202304] |