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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 40 |
| 3 | 200 |
| 4 | 872 |
| 5 | 3720 |
| 6 | 15400 |
| 7 | 62920 |
| 8 | 254440 |
| 9 | 1024648 |
| 10 | 4112680 |
| 11 | 16483400 |
| 12 | 66000360 |
| 13 | 264150920 |
| 14 | 1056903080 |
| 15 | 4228272200 |
| 16 | 16914393832 |
| 17 | 67660396040 |
| 18 | 270647139240 |
| 19 | 1082600410440 |
| 20 | 4330424811880 |
| 21 | 17321748357640 |
| 22 | 69287088965800 |
| 23 | 277148557003720 |
| 24 | 1108594618342760 |
[1,8,40,200,872,3720,15400,62920,254440,1024648, 4112680,16483400,66000360,264150920,1056903080, 4228272200,16914393832,67660396040,270647139240, 1082600410440,4330424811880,17321748357640, 69287088965800,277148557003720,1108594618342760] |