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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 8 |
| 3 | 43 |
| 4 | 190 |
| 5 | 743 |
| 6 | 2668 |
| 7 | 8989 |
| 8 | 28814 |
| 9 | 88720 |
| 10 | 264224 |
| 11 | 765088 |
| 12 | 2162624 |
| 13 | 5986304 |
| 14 | 16268800 |
| 15 | 43499264 |
| 16 | 114629120 |
| 17 | 298147840 |
| 18 | 766361600 |
| 19 | 1948794880 |
| 20 | 4907171840 |
| 21 | 12245598208 |
| 22 | 30305419264 |
| 23 | 74425892864 |
| 24 | 181481635840 |
| 25 | 439603953664 |
[0,1,8,43,190,743,2668,8989,28814,88720,264224, 765088,2162624,5986304,16268800,43499264, 114629120,298147840,766361600,1948794880, 4907171840,12245598208,30305419264,74425892864, 181481635840,439603953664] |