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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 25 |
| 5 | 81 |
| 6 | 267 |
| 7 | 855 |
| 8 | 2865 |
| 9 | 9889 |
| 10 | 34963 |
| 11 | 124455 |
| 12 | 443977 |
| 13 | 1583089 |
| 14 | 5640603 |
| 15 | 20071287 |
| 16 | 71341665 |
| 17 | 253483329 |
| 18 | 901388067 |
| 19 | 3211744839 |
| 20 | 11477295225 |
| 21 | 41157734289 |
| 22 | 148140201003 |
| 23 | 535151245719 |
| 24 | 1939739625873 |
| 25 | 7051722637281 |
[1,1,3,7,25,81,267,855,2865,9889,34963,124455, 443977,1583089,5640603,20071287,71341665, 253483329,901388067,3211744839,11477295225, 41157734289,148140201003,535151245719, 1939739625873,7051722637281] |