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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 20 |
| 3 | 84 |
| 4 | 304 |
| 5 | 1196 |
| 6 | 4280 |
| 7 | 16908 |
| 8 | 67604 |
| 9 | 265124 |
| 10 | 1058244 |
| 11 | 4212368 |
| 12 | 16820404 |
| 13 | 67170488 |
| 14 | 268817820 |
| 15 | 1074835228 |
[1,5,20,84,304,1196,4280,16908,67604,265124, 1058244,4212368,16820404,67170488,268817820, 1074835228] |