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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 16 |
| 5 | 162 |
| 6 | 2004 |
| 7 | 29676 |
| 8 | 511660 |
| 9 | 10077696 |
| 10 | 223416176 |
| 11 | 5508996067 |
| 12 | 149620408779 |
| 13 | 4439426853025 |
| 14 | 142915981606747 |
| 15 | 4962277770372786 |
| 16 | 184884258895036416 |
| 17 | 7358499526831141011 |
| 18 | 311624392527600238320 |
| 19 | 13992684008957401915051 |
| 20 | 664101403687644955591709 |
[1,0,1,3,16,162,2004,29676,511660,10077696, 223416176,5508996067,149620408779,4439426853025, 142915981606747,4962277770372786, 184884258895036416,7358499526831141011, 311624392527600238320,13992684008957401915051, 664101403687644955591709] |