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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 54 |
| 5 | 197 |
| 6 | 792 |
| 7 | 2977 |
| 8 | 11750 |
| 9 | 44744 |
| 10 | 175066 |
| 11 | 671783 |
| 12 | 2619148 |
| 13 | 10104590 |
[1,4,13,54,197,792,2977,11750,44744,175066,671783, 2619148,10104590] |