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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 100 |
| 5 | 3091 |
| 6 | 49375 |
| 7 | 1479104 |
| 8 | 43413488 |
| 9 | 1539619328 |
| 10 | 64563673460 |
| 11 | 2877312739624 |
| 12 | 252631974548628 |
[1,1,3,15,100,3091,49375,1479104,43413488, 1539619328,64563673460,2877312739624, 252631974548628] |