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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 21 |
| 3 | 610 |
| 4 | 6765 |
| 5 | 832040 |
| 6 | 102334155 |
| 7 | 190392490709135 |
| 8 | 1548008755920 |
| 9 | 23416728348467685 |
| 10 | 2880067194370816120 |
| 11 | 81055900096023504197206408605 |
| 12 | 2706074082469569338358691163510069157 |
| 13 | 5358359254990966640871840 |
| 14 | 57602132235424755886206198685365216 |
| 15 | 18547707689471986212190138521399707760 |
[1,2,21,610,6765,832040,102334155,190392490709135, 1548008755920,23416728348467685, 2880067194370816120,81055900096023504197206408605, 2706074082469569338358691163510069157, 5358359254990966640871840, 57602132235424755886206198685365216, 18547707689471986212190138521399707760] |