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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 48 |
| 4 | 291 |
| 5 | 1747 |
| 6 | 10484 |
| 7 | 62904 |
| 8 | 377427 |
| 9 | 2264563 |
| 10 | 13587380 |
| 11 | 81524280 |
| 12 | 489145683 |
| 13 | 2934874099 |
| 14 | 17609244596 |
| 15 | 105655467576 |
| 16 | 633932805459 |
| 17 | 3803596832755 |
| 18 | 22821580996532 |
| 19 | 136929485979192 |
| 20 | 821576915875155 |
| 21 | 4929461495250931 |
[1,8,48,291,1747,10484,62904,377427,2264563, 13587380,81524280,489145683,2934874099, 17609244596,105655467576,633932805459, 3803596832755,22821580996532,136929485979192, 821576915875155,4929461495250931] |