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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 35 |
| 6 | 117 |
| 7 | 411 |
| 8 | 1506 |
| 9 | 5704 |
| 10 | 22264 |
| 11 | 89210 |
| 12 | 364866 |
| 13 | 1519775 |
| 14 | 6428590 |
| 15 | 27566348 |
| 16 | 119608685 |
| 17 | 524401151 |
| 18 | 2320439335 |
| 19 | 10352516502 |
| 20 | 46528515117 |
| 21 | 210506616379 |
| 22 | 958095048741 |
| 23 | 4384343748847 |
| 24 | 20162363200059 |
| 25 | 93139026062773 |
| 26 | 432026004199393 |
| 27 | 2011542030756609 |
| 28 | 9398497710827789 |
[1,1,2,4,12,35,117,411,1506,5704,22264,89210, 364866,1519775,6428590,27566348,119608685, 524401151,2320439335,10352516502,46528515117, 210506616379,958095048741,4384343748847, 20162363200059,93139026062773,432026004199393, 2011542030756609,9398497710827789] |