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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 33 |
| 3 | 193 |
| 4 | 817 |
| 5 | 3553 |
| 6 | 14385 |
| 7 | 58393 |
| 8 | 236281 |
| 9 | 947729 |
| 10 | 3798161 |
| 11 | 15196761 |
| 12 | 60836513 |
| 13 | 243349417 |
| 14 | 973538641 |
| 15 | 3894415281 |
[1,4,33,193,817,3553,14385,58393,236281,947729, 3798161,15196761,60836513,243349417,973538641, 3894415281] |