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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 1 |
| 7 | 5 |
| 8 | 18 |
| 9 | 62 |
| 10 | 226 |
| 11 | 892 |
| 12 | 3835 |
| 13 | 17910 |
| 14 | 90401 |
| 15 | 490421 |
| 16 | 2844970 |
| 17 | 17570207 |
| 18 | 115078228 |
| 19 | 796630963 |
| 20 | 5811215750 |
| 21 | 44551231383 |
| 22 | 358087648032 |
| 23 | 3010990488143 |
| 24 | 26433752431402 |
| 25 | 241852566790848 |
| 26 | 2302304545944415 |
| 27 | 22768248457537798 |
| 28 | 233580248716343376 |
[0,0,0,0,0,1,5,18,62,226,892,3835,17910,90401, 490421,2844970,17570207,115078228,796630963, 5811215750,44551231383,358087648032,3010990488143, 26433752431402,241852566790848,2302304545944415, 22768248457537798,233580248716343376] |