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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 38 |
| 5 | 157 |
| 6 | 524 |
| 7 | 1631 |
| 8 | 4694 |
| 9 | 13006 |
| 10 | 34776 |
| 11 | 90703 |
| 12 | 231788 |
| 13 | 582557 |
| 14 | 1444328 |
| 15 | 3539638 |
| 16 | 8590070 |
| 17 | 20670737 |
| 18 | 49377196 |
| 19 | 117193443 |
| 20 | 276578138 |
| 21 | 649454590 |
| 22 | 1518211492 |
| 23 | 3534848915 |
| 24 | 8200472092 |
| 25 | 18962152697 |
| 26 | 43716887564 |
| 27 | 100516988278 |
[0,0,6,38,157,524,1631,4694,13006,34776,90703, 231788,582557,1444328,3539638,8590070,20670737, 49377196,117193443,276578138,649454590,1518211492, 3534848915,8200472092,18962152697,43716887564, 100516988278] |