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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 40 |
| 3 | 160 |
| 4 | 552 |
| 5 | 1712 |
| 6 | 4896 |
| 7 | 13120 |
| 8 | 33320 |
| 9 | 80872 |
| 10 | 188784 |
| 11 | 425952 |
| 12 | 932640 |
| 13 | 1988080 |
| 14 | 4137024 |
| 15 | 8422848 |
| 16 | 16810536 |
| 17 | 32943760 |
| 18 | 63482760 |
| 19 | 120440608 |
| 20 | 225217904 |
| 21 | 415498496 |
| 22 | 756920160 |
| 23 | 1362645440 |
| 24 | 2425895712 |
| 25 | 4273590392 |
| 26 | 7454092720 |
| 27 | 12879684160 |
| 28 | 22056267840 |
[1,8,40,160,552,1712,4896,13120,33320,80872, 188784,425952,932640,1988080,4137024,8422848, 16810536,32943760,63482760,120440608,225217904, 415498496,756920160,1362645440,2425895712, 4273590392,7454092720,12879684160,22056267840] |