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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 40 |
| 3 | 110 |
| 4 | 780 |
| 5 | 5062 |
| 6 | 31276 |
| 7 | 213912 |
| 8 | 1244680 |
| 9 | 8149652 |
| 10 | 54813300 |
| 11 | 363207297 |
| 12 | 2334210952 |
| 13 | 15099425049 |
| 14 | 99496688244 |
| 15 | 657733281792 |
| 16 | 4291822021778 |
| 17 | 27959094118746 |
| 18 | 183056501656614 |
| 19 | 1201021999376817 |
| 20 | 7872982494463940 |
[3,40,110,780,5062,31276,213912,1244680,8149652, 54813300,363207297,2334210952,15099425049, 99496688244,657733281792,4291822021778, 27959094118746,183056501656614,1201021999376817, 7872982494463940] |