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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 21 |
| 5 | 63 |
| 6 | 117 |
| 7 | 351 |
| 8 | 621 |
| 9 | 1161 |
| 10 | 2043 |
| 11 | 6129 |
| 12 | 8631 |
| 13 | 25893 |
| 14 | 45135 |
| 15 | 71685 |
| 16 | 102285 |
| 17 | 306855 |
| 18 | 420309 |
| 19 | 1260927 |
| 20 | 1755513 |
| 21 | 2671299 |
| 22 | 4571073 |
| 23 | 13713219 |
| 24 | 17156853 |
| 25 | 25778169 |
| 26 | 43930755 |
| 27 | 59315085 |
| 28 | 80765235 |
| 29 | 242295705 |
| 30 | 295267275 |
| 31 | 885801825 |
[1,1,3,9,21,63,117,351,621,1161,2043,6129,8631, 25893,45135,71685,102285,306855,420309,1260927, 1755513,2671299,4571073,13713219,17156853, 25778169,43930755,59315085,80765235,242295705, 295267275,885801825] |