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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 40 |
| 5 | 145 |
| 6 | 526 |
| 7 | 1908 |
| 8 | 6921 |
| 9 | 25105 |
| 10 | 91065 |
| 11 | 330326 |
| 12 | 1198213 |
| 13 | 4346356 |
| 14 | 15765820 |
| 15 | 57188385 |
| 16 | 207443151 |
| 17 | 752472043 |
| 18 | 2729490816 |
| 19 | 9900859685 |
| 20 | 35914032730 |
| 21 | 130273308376 |
| 22 | 472548850273 |
| 23 | 1714107200301 |
| 24 | 6217692609825 |
| 25 | 22553841080350 |
| 26 | 81811015661001 |
[0,1,3,11,40,145,526,1908,6921,25105,91065,330326, 1198213,4346356,15765820,57188385,207443151, 752472043,2729490816,9900859685,35914032730, 130273308376,472548850273,1714107200301, 6217692609825,22553841080350,81811015661001] |