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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 4 |
| 5 | 12 |
| 6 | 0 |
| 7 | 30 |
| 8 | 132 |
| 9 | 342 |
| 10 | 0 |
| 11 | 360 |
| 12 | 2256 |
| 13 | 7416 |
| 14 | 18144 |
| 15 | 0 |
| 16 | 6240 |
| 17 | 54480 |
| 18 | 223920 |
| 19 | 651360 |
| 20 | 1545600 |
| 21 | 0 |
| 22 | 146160 |
| 23 | 1749600 |
| 24 | 8892720 |
| 25 | 30496320 |
| 26 | 82911600 |
| 27 | 193030560 |
| 28 | 0 |
| 29 | 4420080 |
| 30 | 71638560 |
| 31 | 446357520 |
| 32 | 1792405440 |
| 33 | 5552593200 |
| 34 | 14460979680 |
| 35 | 33232948560 |
[1,0,1,0,4,12,0,30,132,342,0,360,2256,7416,18144, 0,6240,54480,223920,651360,1545600,0,146160, 1749600,8892720,30496320,82911600,193030560,0, 4420080,71638560,446357520,1792405440,5552593200, 14460979680,33232948560] |