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| n | a(n) |
|---|---|
| 2 | 2 |
| 3 | 7 |
| 4 | 20 |
| 5 | 56 |
| 6 | 155 |
| 7 | 429 |
| 8 | 1188 |
| 9 | 3298 |
| 10 | 9181 |
| 11 | 25634 |
| 12 | 71781 |
| 13 | 201569 |
| 14 | 567538 |
| 15 | 1601971 |
| 16 | 4532460 |
| 17 | 12851882 |
| 18 | 36516613 |
| 19 | 103955432 |
| 20 | 296471643 |
| 21 | 846932919 |
| 22 | 2423256440 |
| 23 | 6943726380 |
| 24 | 19924638557 |
| 25 | 57247669927 |
| 26 | 164688166948 |
| 27 | 474323305547 |
[2,7,20,56,155,429,1188,3298,9181,25634,71781, 201569,567538,1601971,4532460,12851882,36516613, 103955432,296471643,846932919,2423256440, 6943726380,19924638557,57247669927,164688166948, 474323305547] |