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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 44 |
| 5 | 160 |
| 6 | 576 |
| 7 | 2137 |
| 8 | 8000 |
| 9 | 30112 |
| 10 | 114540 |
| 11 | 436996 |
| 12 | 1676116 |
| 13 | 6453108 |
| 14 | 24911776 |
| 15 | 96460701 |
| 16 | 374292952 |
| 17 | 1455282884 |
| 18 | 5668438104 |
| 19 | 22111680424 |
| 20 | 86375698280 |
| 21 | 337822484240 |
| 22 | 1322699806092 |
| 23 | 5184073262824 |
| 24 | 20336197487948 |
| 25 | 79841329050480 |
| 26 | 313699181900844 |
| 27 | 1233386086431536 |
| 28 | 4852469693781752 |
[1,1,4,13,44,160,576,2137,8000,30112,114540, 436996,1676116,6453108,24911776,96460701, 374292952,1455282884,5668438104,22111680424, 86375698280,337822484240,1322699806092, 5184073262824,20336197487948,79841329050480, 313699181900844,1233386086431536,4852469693781752] |