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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 16 |
| 6 | 39 |
| 7 | 99 |
| 8 | 271 |
| 9 | 763 |
| 10 | 2146 |
| 11 | 6062 |
| 12 | 17359 |
| 13 | 50337 |
| 14 | 147057 |
| 15 | 431874 |
| 16 | 1275273 |
| 17 | 3786649 |
| 18 | 11298031 |
| 19 | 33846202 |
| 20 | 101762937 |
| 21 | 306997821 |
| 22 | 929038518 |
| 23 | 2819426688 |
| 24 | 8578433304 |
| 25 | 26163061776 |
| 26 | 79970186791 |
| 27 | 244938841096 |
| 28 | 751646959402 |
| 29 | 2310683396056 |
| 30 | 7115199919151 |
[1,1,1,2,6,16,39,99,271,763,2146,6062,17359,50337, 147057,431874,1275273,3786649,11298031,33846202, 101762937,306997821,929038518,2819426688, 8578433304,26163061776,79970186791,244938841096, 751646959402,2310683396056,7115199919151] |