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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 78 |
| 5 | 1250 |
| 6 | 29084 |
| 7 | 908408 |
| 8 | 36224616 |
| 9 | 1780689974 |
| 10 | 105135525426 |
| 11 | 7307547766968 |
| 12 | 588450707721862 |
| 13 | 54186944514040018 |
| 14 | 5644227659101270900 |
| 15 | 658939392885787463080 |
| 16 | 85544557333123653732104 |
| 17 | 12265193268786056481323974 |
| 18 | 1930586336858816841621652994 |
[1,1,2,8,78,1250,29084,908408,36224616,1780689974, 105135525426,7307547766968,588450707721862, 54186944514040018,5644227659101270900, 658939392885787463080,85544557333123653732104, 12265193268786056481323974, 1930586336858816841621652994] |