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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 57 |
| 5 | 214 |
| 6 | 979 |
| 7 | 4092 |
| 8 | 19118 |
| 9 | 83810 |
| 10 | 397074 |
| 11 | 1792264 |
| 12 | 8569134 |
| 13 | 39449523 |
| 14 | 189833114 |
| 15 | 886149501 |
| 16 | 4284798960 |
| 17 | 20208047001 |
| 18 | 98076614702 |
| 19 | 466207454479 |
| 20 | 2269386827433 |
| 21 | 10854652323409 |
| 22 | 52966000595103 |
| 23 | 254608932972014 |
| 24 | 1244890116366611 |
| 25 | 6008783649970492 |
| 26 | 29429687121612288 |
| 27 | 142535485722942391 |
[1,1,4,13,57,214,979,4092,19118,83810,397074, 1792264,8569134,39449523,189833114,886149501, 4284798960,20208047001,98076614702,466207454479, 2269386827433,10854652323409,52966000595103, 254608932972014,1244890116366611,6008783649970492, 29429687121612288,142535485722942391] |