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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 12 |
| 3 | 34 |
| 4 | 92 |
| 5 | 242 |
| 6 | 627 |
| 7 | 1608 |
| 8 | 4096 |
| 9 | 10388 |
| 10 | 26269 |
| 11 | 66304 |
| 12 | 167161 |
| 13 | 421162 |
| 14 | 1060816 |
| 15 | 2671908 |
| 16 | 6730941 |
| 17 | 16961430 |
| 18 | 42758695 |
| 19 | 107843080 |
| 20 | 272136858 |
| 21 | 687106696 |
| 22 | 1735849310 |
| 23 | 4387895300 |
| 24 | 11098372185 |
| 25 | 28088028612 |
| 26 | 71128006458 |
| 27 | 180224822694 |
[1,4,12,34,92,242,627,1608,4096,10388,26269,66304, 167161,421162,1060816,2671908,6730941,16961430, 42758695,107843080,272136858,687106696,1735849310, 4387895300,11098372185,28088028612,71128006458, 180224822694] |