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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 4 |
| 5 | 6 |
| 6 | 10 |
| 7 | 21 |
| 8 | 48 |
| 9 | 197 |
| 10 | 3854 |
| 11 | 911 |
| 12 | 4705 |
| 13 | 69137 |
| 14 | 25797 |
| 15 | 232944 |
| 16 | 466932 |
| 17 | 3110924 |
| 18 | 4670197 |
| 19 | 20851430 |
| 20 | 80081977 |
| 21 | 987827086 |
| 22 | 1470388038 |
| 23 | 6545264485 |
| 24 | 35778005903 |
| 25 | 179227960118 |
| 26 | 797794938348 |
| 27 | 79971185783965 |
| 28 | 17084369697743 |
| 29 | 227738431773765 |
| 30 | 1024021410267278 |
[0,0,0,0,4,6,10,21,48,197,3854,911,4705,69137, 25797,232944,466932,3110924,4670197,20851430, 80081977,987827086,1470388038,6545264485, 35778005903,179227960118,797794938348, 79971185783965,17084369697743,227738431773765, 1024021410267278] |