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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 15 |
| 3 | 263 |
| 4 | 8450 |
| 5 | 432514 |
| 6 | 32308948 |
| 7 | 3317537208 |
| 8 | 448304831744 |
| 9 | 77131843774416 |
| 10 | 16463316260454624 |
| 11 | 4269057157148962320 |
| 12 | 1321883141629335120576 |
| 13 | 481761671427370573812000 |
| 14 | 204137795884403682574690176 |
| 15 | 99514256070766872294586292544 |
[1,2,15,263,8450,432514,32308948,3317537208, 448304831744,77131843774416,16463316260454624, 4269057157148962320,1321883141629335120576, 481761671427370573812000, 204137795884403682574690176, 99514256070766872294586292544] |