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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 48 |
| 5 | 197 |
| 6 | 808 |
| 7 | 3318 |
| 8 | 13626 |
| 9 | 55961 |
| 10 | 229829 |
| 11 | 943899 |
| 12 | 3876559 |
| 13 | 15920890 |
| 14 | 65386531 |
| 15 | 268540168 |
| 16 | 1102884965 |
| 17 | 4529509517 |
| 18 | 18602535276 |
| 19 | 76399953992 |
| 20 | 313771907077 |
| 21 | 1288650117266 |
| 22 | 5292440423364 |
| 23 | 21735865507300 |
| 24 | 89268430356963 |
| 25 | 366622284064081 |
| 26 | 1505704745058057 |
[0,1,3,12,48,197,808,3318,13626,55961,229829, 943899,3876559,15920890,65386531,268540168, 1102884965,4529509517,18602535276,76399953992, 313771907077,1288650117266,5292440423364, 21735865507300,89268430356963,366622284064081, 1505704745058057] |