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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 20 |
| 3 | 0 |
| 4 | 790 |
| 5 | 0 |
| 6 | 34042 |
| 7 | 0 |
| 8 | 1470618 |
| 9 | 0 |
| 10 | 63526554 |
| 11 | 0 |
| 12 | 2744129114 |
| 13 | 0 |
| 14 | 118536728562 |
| 15 | 0 |
| 16 | 5120367434418 |
| 17 | 0 |
| 18 | 221181729631882 |
| 19 | 0 |
| 20 | 9554266491058090 |
| 21 | 0 |
| 22 | 412710429318366178 |
| 23 | 0 |
| 24 | 17827626812331482594 |
| 25 | 0 |
| 26 | 770090248640353835354 |
| 27 | 0 |
[0,20,0,790,0,34042,0,1470618,0,63526554,0, 2744129114,0,118536728562,0,5120367434418,0, 221181729631882,0,9554266491058090,0, 412710429318366178,0,17827626812331482594,0, 770090248640353835354,0] |