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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 14 |
| 5 | 66 |
| 6 | 392 |
| 7 | 2806 |
| 8 | 23490 |
| 9 | 225104 |
| 10 | 2429538 |
| 11 | 29159162 |
| 12 | 385196964 |
| 13 | 5553689194 |
| 14 | 86776290538 |
| 15 | 1460602599748 |
| 16 | 26346881876166 |
| 17 | 507037223792778 |
| 18 | 10369313541925896 |
| 19 | 224565589119822926 |
| 20 | 5134144053785703610 |
| 21 | 123569877999804177120 |
| 22 | 3123085821618415219082 |
[1,2,4,14,66,392,2806,23490,225104,2429538, 29159162,385196964,5553689194,86776290538, 1460602599748,26346881876166,507037223792778, 10369313541925896,224565589119822926, 5134144053785703610,123569877999804177120, 3123085821618415219082] |