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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 21 |
| 2 | 298 |
| 3 | 3570 |
| 4 | 38971 |
| 5 | 401751 |
| 6 | 3988468 |
| 7 | 38583300 |
| 8 | 366449941 |
| 9 | 3434404281 |
| 10 | 31873887838 |
| 11 | 293663563830 |
| 12 | 2690806228111 |
| 13 | 24553315831611 |
| 14 | 223338364450408 |
| 15 | 2026585451393160 |
| 16 | 18355202849805481 |
| 17 | 166009125098571741 |
| 18 | 1499772036736668178 |
| 19 | 13537796780062999290 |
[1,21,298,3570,38971,401751,3988468,38583300, 366449941,3434404281,31873887838,293663563830, 2690806228111,24553315831611,223338364450408, 2026585451393160,18355202849805481, 166009125098571741,1499772036736668178, 13537796780062999290] |