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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 9 |
| 3 | 25 |
| 4 | 109 |
| 5 | 381 |
| 6 | 1421 |
| 7 | 5069 |
| 8 | 18075 |
| 9 | 63499 |
| 10 | 221323 |
| 11 | 764523 |
| 12 | 2621587 |
| 13 | 8928115 |
| 14 | 30220347 |
| 15 | 101721707 |
| 16 | 340659227 |
| 17 | 1135543323 |
| 18 | 3769023795 |
| 19 | 12460643043 |
| 20 | 41045661279 |
| 21 | 134748546639 |
| 22 | 440974812831 |
| 23 | 1438893866655 |
| 24 | 4682226213021 |
| 25 | 15197079464301 |
| 26 | 49206276341901 |
[1,1,9,25,109,381,1421,5069,18075,63499,221323, 764523,2621587,8928115,30220347,101721707, 340659227,1135543323,3769023795,12460643043, 41045661279,134748546639,440974812831, 1438893866655,4682226213021,15197079464301, 49206276341901] |