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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 7 |
| 3 | 56 |
| 4 | 418 |
| 5 | 3091 |
| 6 | 22845 |
| 7 | 168803 |
| 8 | 1247297 |
| 9 | 9216353 |
| 10 | 68100150 |
| 11 | 503195828 |
| 12 | 3718142207 |
| 13 | 27473561357 |
| 14 | 203003686105 |
| 15 | 1500005624923 |
| 16 | 11083625711270 |
| 17 | 81897532160124 |
| 18 | 605145459495140 |
| 19 | 4471453748222756 |
| 20 | 33039822589391675 |
[0,7,56,418,3091,22845,168803,1247297,9216353, 68100150,503195828,3718142207,27473561357, 203003686105,1500005624923,11083625711270, 81897532160124,605145459495140,4471453748222756, 33039822589391675] |