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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 12 |
| 3 | 38 |
| 4 | 112 |
| 5 | 332 |
| 6 | 972 |
| 7 | 2818 |
| 8 | 8098 |
| 9 | 23096 |
| 10 | 65418 |
| 11 | 184194 |
| 12 | 516080 |
| 13 | 1440334 |
| 14 | 4008442 |
| 15 | 11135682 |
| 16 | 30912896 |
| 17 | 85835538 |
| 18 | 238601354 |
| 19 | 664447912 |
| 20 | 1854592214 |
| 21 | 5189848462 |
| 22 | 14561237108 |
| 23 | 40954656118 |
| 24 | 115428662380 |
| 25 | 325847049200 |
| 26 | 920772219740 |
| 27 | 2602948470362 |
| 28 | 7356994944096 |
| 29 | 20779322594048 |
[1,4,12,38,112,332,972,2818,8098,23096,65418, 184194,516080,1440334,4008442,11135682,30912896, 85835538,238601354,664447912,1854592214, 5189848462,14561237108,40954656118,115428662380, 325847049200,920772219740,2602948470362, 7356994944096,20779322594048] |