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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 13 |
| 5 | 12 |
| 6 | -121 |
| 7 | -896 |
| 8 | -4391 |
| 9 | -10160 |
| 10 | 64491 |
| 11 | 900768 |
| 12 | 6118693 |
| 13 | 16033344 |
| 14 | -198382609 |
| 15 | -3101259776 |
| 16 | -22263439439 |
| 17 | -23508393728 |
| 18 | 1747001723475 |
| 19 | 24367272291840 |
| 20 | 145393520219965 |
[1,1,3,6,13,12,-121,-896,-4391,-10160,64491, 900768,6118693,16033344,-198382609,-3101259776, -22263439439,-23508393728,1747001723475, 24367272291840,145393520219965] |