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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 5 |
| 3 | 1 |
| 4 | 19 |
| 5 | 30 |
| 6 | 102 |
| 7 | 242 |
| 8 | 666 |
| 9 | 1718 |
| 10 | 4555 |
| 11 | 11937 |
| 12 | 31435 |
| 13 | 82615 |
| 14 | 217301 |
| 15 | 571372 |
| 16 | 1502572 |
| 17 | 3951188 |
| 18 | 10390340 |
| 19 | 27322972 |
| 20 | 71850149 |
| 21 | 188941251 |
| 22 | 496850977 |
| 23 | 1306548125 |
| 24 | 3435774983 |
| 25 | 9034913514 |
| 26 | 23758733842 |
| 27 | 62477347430 |
| 28 | 164294064510 |
| 29 | 432037221810 |
[1,-1,5,1,19,30,102,242,666,1718,4555,11937,31435, 82615,217301,571372,1502572,3951188,10390340, 27322972,71850149,188941251,496850977,1306548125, 3435774983,9034913514,23758733842,62477347430, 164294064510,432037221810] |