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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 20 |
| 3 | 74 |
| 4 | 347 |
| 5 | 1743 |
| 6 | 8385 |
| 7 | 44355 |
| 8 | 229952 |
| 9 | 1235489 |
| 10 | 6629026 |
| 11 | 37152645 |
| 12 | 202017712 |
| 13 | 1142393492 |
| 14 | 6333190658 |
[4,20,74,347,1743,8385,44355,229952,1235489, 6629026,37152645,202017712,1142393492,6333190658] |