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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 18 |
| 5 | 60 |
| 6 | 203 |
| 7 | 725 |
| 8 | 2772 |
| 9 | 11368 |
| 10 | 49853 |
| 11 | 232757 |
| 12 | 1151902 |
| 13 | 6018772 |
| 14 | 33087191 |
| 15 | 190780197 |
| 16 | 1150653904 |
| 17 | 7241710912 |
| 18 | 47454745785 |
| 19 | 323154696165 |
| 20 | 2282779990474 |
| 21 | 16700904488684 |
| 22 | 126356632390275 |
| 23 | 987303454928949 |
[0,1,5,18,60,203,725,2772,11368,49853,232757, 1151902,6018772,33087191,190780197,1150653904, 7241710912,47454745785,323154696165,2282779990474, 16700904488684,126356632390275,987303454928949] |