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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 8 |
| 5 | 20 |
| 6 | 50 |
| 7 | 128 |
| 8 | 326 |
| 9 | 838 |
| 10 | 2164 |
| 11 | 5613 |
| 12 | 14619 |
| 13 | 38200 |
| 14 | 100109 |
| 15 | 263002 |
| 16 | 692452 |
| 17 | 1826640 |
| 18 | 4826740 |
| 19 | 12773610 |
| 20 | 33850507 |
| 21 | 89815472 |
| 22 | 238573535 |
| 23 | 634359840 |
| 24 | 1688317073 |
| 25 | 4497222961 |
| 26 | 11988860360 |
| 27 | 31983701435 |
| 28 | 85383496739 |
| 29 | 228083043888 |
[0,1,3,8,20,50,128,326,838,2164,5613,14619,38200, 100109,263002,692452,1826640,4826740,12773610, 33850507,89815472,238573535,634359840,1688317073, 4497222961,11988860360,31983701435,85383496739, 228083043888] |