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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 25 |
| 5 | 75 |
| 6 | 223 |
| 7 | 665 |
| 8 | 1993 |
| 9 | 5971 |
| 10 | 17903 |
| 11 | 53697 |
| 12 | 161065 |
| 13 | 483163 |
| 14 | 1449439 |
| 15 | 4348233 |
| 16 | 13044585 |
| 17 | 39133571 |
| 18 | 117400431 |
| 19 | 352200881 |
| 20 | 1056601993 |
| 21 | 3169805003 |
| 22 | 9509413535 |
| 23 | 28528238329 |
| 24 | 85584711561 |
| 25 | 256754129459 |
| 26 | 770262380399 |
| 27 | 2310787129121 |
| 28 | 6932361368937 |
[0,1,3,9,25,75,223,665,1993,5971,17903,53697, 161065,483163,1449439,4348233,13044585,39133571, 117400431,352200881,1056601993,3169805003, 9509413535,28528238329,85584711561,256754129459, 770262380399,2310787129121,6932361368937] |