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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 6 |
| 5 | 0 |
| 6 | 16 |
| 7 | 12 |
| 8 | 54 |
| 9 | 72 |
| 10 | 204 |
| 11 | 372 |
| 12 | 970 |
| 13 | 1800 |
| 14 | 5412 |
| 15 | 10268 |
| 16 | 28830 |
| 17 | 61752 |
| 18 | 157974 |
| 19 | 375360 |
| 20 | 937542 |
| 21 | 2327760 |
| 22 | 5929068 |
| 23 | 14655120 |
| 24 | 38155964 |
| 25 | 94792968 |
| 26 | 248594928 |
| 27 | 630264816 |
| 28 | 1652484378 |
| 29 | 4261164096 |
| 30 | 11190811568 |
| 31 | 29116821504 |
[1,0,0,0,6,0,16,12,54,72,204,372,970,1800,5412, 10268,28830,61752,157974,375360,937542,2327760, 5929068,14655120,38155964,94792968,248594928, 630264816,1652484378,4261164096,11190811568, 29116821504] |