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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 0 |
| 3 | 2 |
| 4 | 0 |
| 5 | 4 |
| 6 | 6 |
| 7 | 8 |
| 8 | 24 |
| 9 | 52 |
| 10 | 96 |
| 11 | 212 |
| 12 | 504 |
| 13 | 1072 |
| 14 | 2352 |
| 15 | 5288 |
| 16 | 11928 |
| 17 | 26800 |
| 18 | 60336 |
| 19 | 136304 |
| 20 | 308928 |
| 21 | 701248 |
| 22 | 1593120 |
| 23 | 3622016 |
| 24 | 8245008 |
| 25 | 18787360 |
| 26 | 42836928 |
| 27 | 97724384 |
| 28 | 223052784 |
| 29 | 509338816 |
| 30 | 1163512032 |
| 31 | 2658731648 |
| 32 | 6077117376 |
| 33 | 13893874624 |
| 34 | 31771515648 |
[1,1,0,2,0,4,6,8,24,52,96,212,504,1072,2352,5288, 11928,26800,60336,136304,308928,701248,1593120, 3622016,8245008,18787360,42836928,97724384, 223052784,509338816,1163512032,2658731648, 6077117376,13893874624,31771515648] |