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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 12 |
| 4 | 36 |
| 5 | 90 |
| 6 | 286 |
| 7 | 728 |
| 8 | 2380 |
| 9 | 6120 |
| 10 | 20349 |
| 11 | 52668 |
| 12 | 177100 |
| 13 | 460460 |
| 14 | 1560780 |
| 15 | 4071600 |
| 16 | 13884156 |
| 17 | 36312408 |
| 18 | 124403620 |
| 19 | 326023280 |
| 20 | 1121099408 |
| 21 | 2942885946 |
| 22 | 10150595910 |
| 23 | 26681566392 |
| 24 | 92263734836 |
| 25 | 242799302200 |
| 26 | 841392966470 |
| 27 | 2216352204360 |
| 28 | 7694644696200 |
[1,2,5,12,36,90,286,728,2380,6120,20349,52668, 177100,460460,1560780,4071600,13884156,36312408, 124403620,326023280,1121099408,2942885946, 10150595910,26681566392,92263734836,242799302200, 841392966470,2216352204360,7694644696200] |