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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 13 |
| 3 | 48 |
| 4 | 557 |
| 5 | 3632 |
| 6 | 30769 |
| 7 | 229248 |
| 8 | 1815601 |
| 9 | 13960720 |
| 10 | 108880333 |
| 11 | 843387440 |
| 12 | 6554347309 |
| 13 | 50856496800 |
| 14 | 394905287105 |
| 15 | 3065356528128 |
| 16 | 23798261444545 |
| 17 | 184745059744352 |
| 18 | 1434227515809901 |
| 19 | 11134091807034928 |
| 20 | 86436190372455949 |
[0,13,48,557,3632,30769,229248,1815601,13960720, 108880333,843387440,6554347309,50856496800, 394905287105,3065356528128,23798261444545, 184745059744352,1434227515809901, 11134091807034928,86436190372455949] |