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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 8 |
| 6 | 32 |
| 7 | 118 |
| 8 | 440 |
| 9 | 1664 |
| 10 | 6354 |
| 11 | 24360 |
| 12 | 93440 |
| 13 | 358246 |
| 14 | 1372824 |
| 15 | 5259424 |
| 16 | 20147874 |
| 17 | 77183048 |
| 18 | 295680992 |
| 19 | 1132742102 |
| 20 | 4339515256 |
| 21 | 16624624832 |
| 22 | 63688678130 |
| 23 | 243990165864 |
| 24 | 934721535168 |
| 25 | 3580899428294 |
| 26 | 13718353772632 |
[0,0,0,2,8,32,118,440,1664,6354,24360,93440, 358246,1372824,5259424,20147874,77183048, 295680992,1132742102,4339515256,16624624832, 63688678130,243990165864,934721535168, 3580899428294,13718353772632] |