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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 8 |
| 3 | 20 |
| 4 | 52 |
| 5 | 136 |
| 6 | 360 |
| 7 | 960 |
| 8 | 2576 |
| 9 | 6944 |
| 10 | 18784 |
| 11 | 50944 |
| 12 | 138432 |
| 13 | 376704 |
| 14 | 1026176 |
| 15 | 2797568 |
| 16 | 7631104 |
| 17 | 20824576 |
| 18 | 56845824 |
| 19 | 155209728 |
| 20 | 423848960 |
| 21 | 1157593088 |
| 22 | 3161835520 |
| 23 | 8636760064 |
| 24 | 23592996864 |
| 25 | 64451125248 |
| 26 | 176071467008 |
| 27 | 481011630080 |
[2,8,20,52,136,360,960,2576,6944,18784,50944, 138432,376704,1026176,2797568,7631104,20824576, 56845824,155209728,423848960,1157593088, 3161835520,8636760064,23592996864,64451125248, 176071467008,481011630080] |