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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 16 |
| 5 | 153 |
| 6 | 71838 |
| 7 | 5965398 |
| 8 | 2614508085 |
| 9 | 9822629511079 |
| 10 | 28751930151895611 |
| 11 | 162231215752303027270 |
| 12 | 32813942272624544838651213 |
| 13 | 1257159787425487037702548758466 |
[1,1,4,16,153,71838,5965398,2614508085, 9822629511079,28751930151895611, 162231215752303027270,32813942272624544838651213, 1257159787425487037702548758466] |