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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 6 |
| 6 | 16 |
| 7 | 18 |
| 8 | 54 |
| 9 | 58 |
| 10 | 100 |
| 11 | 120 |
| 12 | 504 |
| 13 | 1302 |
| 14 | 3234 |
| 15 | 14748 |
| 16 | 16102 |
| 17 | 22782 |
| 18 | 34656 |
| 19 | 64764 |
| 20 | 70866 |
| 21 | 194940 |
| 22 | 274074 |
| 23 | 313344 |
| 24 | 331416 |
| 25 | 354640 |
[0,1,2,4,6,16,18,54,58,100,120,504,1302,3234, 14748,16102,22782,34656,64764,70866,194940,274074, 313344,331416,354640] |