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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 18 |
| 2 | 76 |
| 3 | 322 |
| 4 | 1360 |
| 5 | 5744 |
| 6 | 24256 |
| 7 | 102428 |
| 8 | 432528 |
| 9 | 1826456 |
| 10 | 7712656 |
| 11 | 32568568 |
| 12 | 137528704 |
| 13 | 580748416 |
| 14 | 2452351488 |
| 15 | 10355650832 |
| 16 | 43729255232 |
| 17 | 184657419808 |
| 18 | 779760883392 |
| 19 | 3292730050592 |
| 20 | 13904353779456 |
| 21 | 58714516845824 |
| 22 | 247936332973056 |
| 23 | 1046971490364864 |
[4,18,76,322,1360,5744,24256,102428,432528, 1826456,7712656,32568568,137528704,580748416, 2452351488,10355650832,43729255232,184657419808, 779760883392,3292730050592,13904353779456, 58714516845824,247936332973056,1046971490364864] |