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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 14 |
| 3 | 48 |
| 4 | 166 |
| 5 | 584 |
| 6 | 2094 |
| 7 | 7648 |
| 8 | 28406 |
| 9 | 107064 |
| 10 | 408574 |
| 11 | 1575248 |
| 12 | 6123846 |
| 13 | 23963944 |
| 14 | 94261454 |
| 15 | 372262848 |
| 16 | 1474702486 |
| 17 | 5855763224 |
| 18 | 23293912734 |
| 19 | 92788230448 |
| 20 | 369990660326 |
| 21 | 1476475856904 |
| 22 | 5895443074414 |
| 23 | 23550391238048 |
[1,4,14,48,166,584,2094,7648,28406,107064,408574, 1575248,6123846,23963944,94261454,372262848, 1474702486,5855763224,23293912734,92788230448, 369990660326,1476475856904,5895443074414, 23550391238048] |