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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 34 |
| 6 | 205 |
| 7 | 1456 |
| 8 | 11837 |
| 9 | 108150 |
| 10 | 1096011 |
| 11 | 12196128 |
| 12 | 147814359 |
| 13 | 1938062490 |
| 14 | 27333191613 |
| 15 | 412614191808 |
| 16 | 6638401596645 |
| 17 | 113398127795862 |
| 18 | 2049808094564139 |
| 19 | 39091473755006400 |
| 20 | 784404343854767727 |
| 21 | 16520634668922810426 |
| 22 | 364400233756422553053 |
[0,1,1,2,7,34,205,1456,11837,108150,1096011, 12196128,147814359,1938062490,27333191613, 412614191808,6638401596645,113398127795862, 2049808094564139,39091473755006400, 784404343854767727,16520634668922810426, 364400233756422553053] |