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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 9 |
| 4 | 63 |
| 5 | 108 |
| 6 | 324 |
| 7 | 828 |
| 8 | 1989 |
| 9 | 4635 |
| 10 | 10845 |
| 11 | 24363 |
| 12 | 54279 |
| 13 | 118827 |
| 14 | 258705 |
| 15 | 565389 |
| 16 | 1216134 |
| 17 | 2611359 |
| 18 | 5584518 |
| 19 | 11875977 |
| 20 | 25184205 |
| 21 | 53209728 |
| 22 | 112069377 |
| 23 | 235502361 |
| 24 | 493827687 |
| 25 | 1033041267 |
| 26 | 2156974227 |
| 27 | 4495662081 |
| 28 | 9355185828 |
| 29 | 19437382512 |
| 30 | 40329016200 |
[1,2,6,9,63,108,324,828,1989,4635,10845,24363, 54279,118827,258705,565389,1216134,2611359, 5584518,11875977,25184205,53209728,112069377, 235502361,493827687,1033041267,2156974227, 4495662081,9355185828,19437382512,40329016200] |