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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 34 |
| 4 | 410 |
| 5 | 6455 |
| 6 | 125251 |
| 7 | 2888305 |
| 8 | 77157780 |
| 9 | 2342972405 |
| 10 | 79701049425 |
| 11 | 3002132647515 |
| 12 | 124039845584382 |
| 13 | 5577660227565634 |
| 14 | 271162541308698623 |
| 15 | 14172237715785139175 |
| 16 | 792418822364402364530 |
| 17 | 47198077739119663907870 |
| 18 | 2983413619934353599892285 |
[1,1,4,34,410,6455,125251,2888305,77157780, 2342972405,79701049425,3002132647515, 124039845584382,5577660227565634, 271162541308698623,14172237715785139175, 792418822364402364530,47198077739119663907870, 2983413619934353599892285] |