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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 12 |
| 3 | 48 |
| 4 | 144 |
| 5 | 576 |
| 6 | 1728 |
| 7 | 6912 |
| 8 | 20736 |
| 9 | 82944 |
| 10 | 248832 |
| 11 | 995328 |
| 12 | 2985984 |
| 13 | 11943936 |
| 14 | 35831808 |
| 15 | 143327232 |
| 16 | 429981696 |
| 17 | 1719926784 |
| 18 | 5159780352 |
| 19 | 20639121408 |
| 20 | 61917364224 |
| 21 | 247669456896 |
| 22 | 743008370688 |
| 23 | 2972033482752 |
| 24 | 8916100448256 |
| 25 | 35664401793024 |
| 26 | 106993205379072 |
| 27 | 427972821516288 |
[1,4,12,48,144,576,1728,6912,20736,82944,248832, 995328,2985984,11943936,35831808,143327232, 429981696,1719926784,5159780352,20639121408, 61917364224,247669456896,743008370688, 2972033482752,8916100448256,35664401793024, 106993205379072,427972821516288] |