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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 10 |
| 4 | 28 |
| 5 | 82 |
| 6 | 244 |
| 7 | 730 |
| 8 | 2188 |
| 9 | 6562 |
| 10 | 19684 |
| 11 | 59050 |
| 12 | 177148 |
| 13 | 531442 |
| 14 | 1594324 |
| 15 | 4782970 |
| 16 | 14348908 |
| 17 | 43046722 |
| 18 | 129140164 |
| 19 | 387420490 |
| 20 | 1162261468 |
| 21 | 3486784402 |
| 22 | 10460353204 |
| 23 | 31381059610 |
| 24 | 94143178828 |
| 25 | 282429536482 |
| 26 | 847288609444 |
[1,2,4,10,28,82,244,730,2188,6562,19684,59050, 177148,531442,1594324,4782970,14348908,43046722, 129140164,387420490,1162261468,3486784402, 10460353204,31381059610,94143178828,282429536482, 847288609444] |