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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 36 |
| 5 | 176 |
| 6 | 824 |
| 7 | 3668 |
| 8 | 15808 |
| 9 | 66640 |
| 10 | 276184 |
| 11 | 1129482 |
| 12 | 4570084 |
| 13 | 18329920 |
| 14 | 72981648 |
| 15 | 288779688 |
| 16 | 1136580576 |
| 17 | 4452663936 |
| 18 | 17372989712 |
| 19 | 67541322638 |
| 20 | 261743811012 |
| 21 | 1011439313456 |
| 22 | 3898369209992 |
| 23 | 14990343112316 |
| 24 | 57519762677984 |
[0,0,6,36,176,824,3668,15808,66640,276184,1129482, 4570084,18329920,72981648,288779688,1136580576, 4452663936,17372989712,67541322638,261743811012, 1011439313456,3898369209992,14990343112316, 57519762677984] |