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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 40 |
| 5 | 313 |
| 6 | 3090 |
| 7 | 36767 |
| 8 | 511648 |
| 9 | 8149601 |
| 10 | 146181170 |
| 11 | 2915473799 |
| 12 | 63994242408 |
| 13 | 1532946343993 |
| 14 | 39792610701410 |
| 15 | 1112660153295487 |
| 16 | 33340011988163200 |
| 17 | 1065767723467926913 |
| 18 | 36202762585921351842 |
| 19 | 1302233685369700739399 |
| 20 | 49448677281462706745320 |
[1,2,7,40,313,3090,36767,511648,8149601,146181170, 2915473799,63994242408,1532946343993, 39792610701410,1112660153295487,33340011988163200, 1065767723467926913,36202762585921351842, 1302233685369700739399,49448677281462706745320] |