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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 22 |
| 3 | 213 |
| 4 | 1724 |
| 5 | 12955 |
| 6 | 93306 |
| 7 | 653177 |
| 8 | 4478968 |
| 9 | 30233079 |
| 10 | 201553910 |
| 11 | 1330255861 |
| 12 | 8707129332 |
| 13 | 56596340723 |
| 14 | 365699432434 |
| 15 | 2350924922865 |
| 16 | 15045919506416 |
| 17 | 95917736853487 |
| 18 | 609359740010478 |
| 19 | 3859278353399789 |
| 20 | 24374389600419820 |
[1,22,213,1724,12955,93306,653177,4478968, 30233079,201553910,1330255861,8707129332, 56596340723,365699432434,2350924922865, 15045919506416,95917736853487,609359740010478, 3859278353399789,24374389600419820] |