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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 16 |
| 3 | 405 |
| 4 | 672320 |
| 5 | 1352290629546 |
| 6 | 4817801789405093582066881 |
| 7 | 125242334906904794515426191021121381708761081802849 |
| 8 | 48098205042808280233282792304806428848378744166690329294696649253234314988369597043479633480454760546 |
[1,3,16,405,672320,1352290629546, 4817801789405093582066881, 12524233490690479451542619102112138170876108180284\ 9, 48098205042808280233282792304806428848378744166690\ 32929469664925323431498836959704347963348045476054\ 6] |