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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 34 |
| 5 | 387 |
| 6 | 5596 |
| 7 | 97149 |
| 8 | 1959938 |
| 9 | 44956945 |
| 10 | 1154208544 |
| 11 | 32772977715 |
| 12 | 1019467710328 |
| 13 | 34473686833527 |
| 14 | 1259038828370402 |
| 15 | 49388615245426933 |
| 16 | 2070991708598960524 |
| 17 | 92445181295983865757 |
| 18 | 4376733266230674345874 |
| 19 | 219058079619119072854095 |
| 20 | 11556990682657196214302036 |
[1,0,1,4,34,387,5596,97149,1959938,44956945, 1154208544,32772977715,1019467710328, 34473686833527,1259038828370402,49388615245426933, 2070991708598960524,92445181295983865757, 4376733266230674345874,219058079619119072854095, 11556990682657196214302036] |