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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 23 |
| 5 | 106 |
| 6 | 493 |
| 7 | 2312 |
| 8 | 10917 |
| 9 | 51840 |
| 10 | 247319 |
| 11 | 1184557 |
| 12 | 5692517 |
| 13 | 27434578 |
| 14 | 132547877 |
| 15 | 641789941 |
| 16 | 3113487683 |
| 17 | 15130119784 |
| 18 | 73637665027 |
| 19 | 358883327591 |
| 20 | 1751237017413 |
| 21 | 8555108199294 |
| 22 | 41836182269267 |
| 23 | 204779733440086 |
[0,0,1,5,23,106,493,2312,10917,51840,247319, 1184557,5692517,27434578,132547877,641789941, 3113487683,15130119784,73637665027,358883327591, 1751237017413,8555108199294,41836182269267, 204779733440086] |