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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 17 |
| 6 | 54 |
| 7 | 178 |
| 8 | 606 |
| 9 | 2116 |
| 10 | 7533 |
| 11 | 27242 |
| 12 | 99799 |
| 13 | 369583 |
| 14 | 1381309 |
| 15 | 5203599 |
| 16 | 19737935 |
| 17 | 75321337 |
| 18 | 288968031 |
| 19 | 1113893815 |
| 20 | 4312073256 |
| 21 | 16756934181 |
| 22 | 65345024968 |
| 23 | 255625711296 |
| 24 | 1002888257745 |
| 25 | 3945055462020 |
| 26 | 15556613282788 |
[1,1,2,6,17,54,178,606,2116,7533,27242,99799, 369583,1381309,5203599,19737935,75321337, 288968031,1113893815,4312073256,16756934181, 65345024968,255625711296,1002888257745, 3945055462020,15556613282788] |