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| n | a(n) |
|---|---|
| 1 | 40 |
| 2 | 167 |
| 3 | 639 |
| 4 | 2375 |
| 5 | 8625 |
| 6 | 30952 |
| 7 | 110187 |
| 8 | 390391 |
| 9 | 1378890 |
| 10 | 4860979 |
| 11 | 17115235 |
| 12 | 60214730 |
| 13 | 211741401 |
| 14 | 744338632 |
| 15 | 2616055529 |
| 16 | 9193203944 |
| 17 | 32303585679 |
| 18 | 113504084395 |
| 19 | 398802149195 |
| 20 | 1401180399346 |
| 21 | 4922940442496 |
| 22 | 17296221980468 |
[40,167,639,2375,8625,30952,110187,390391,1378890, 4860979,17115235,60214730,211741401,744338632, 2616055529,9193203944,32303585679,113504084395, 398802149195,1401180399346,4922940442496, 17296221980468] |