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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | 6 |
| 4 | 8 |
| 5 | 30 |
| 6 | 60 |
| 7 | 154 |
| 8 | 336 |
| 9 | 774 |
| 10 | 1700 |
| 11 | 3762 |
| 12 | 8184 |
| 13 | 17758 |
| 14 | 38220 |
| 15 | 81930 |
| 16 | 174752 |
| 17 | 371382 |
| 18 | 786420 |
| 19 | 1660258 |
| 20 | 3495240 |
| 21 | 7340046 |
| 22 | 15379100 |
| 23 | 32156346 |
| 24 | 67108848 |
| 25 | 139810150 |
| 26 | 290805060 |
| 27 | 603979794 |
| 28 | 1252698776 |
| 29 | 2594876094 |
| 30 | 5368709100 |
[0,1,0,6,8,30,60,154,336,774,1700,3762,8184,17758, 38220,81930,174752,371382,786420,1660258,3495240, 7340046,15379100,32156346,67108848,139810150, 290805060,603979794,1252698776,2594876094, 5368709100] |