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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 33 |
| 4 | 472 |
| 5 | 3245 |
| 6 | 157896 |
| 7 | 828583 |
| 8 | 132078976 |
| 9 | 1578211209 |
| 10 | 307174074400 |
| 11 | 285351587411 |
| 12 | 1835340563252736 |
| 13 | 302881333613053 |
| 14 | 11743240652094910336 |
| 15 | 336123967242674523375 |
| 16 | 149825956013958069846016 |
| 17 | 827240617573764860177 |
| 18 | 3551697093896307129060647424 |
[1,6,33,472,3245,157896,828583,132078976, 1578211209,307174074400,285351587411, 1835340563252736,302881333613053, 11743240652094910336,336123967242674523375, 149825956013958069846016,827240617573764860177, 3551697093896307129060647424] |