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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 37 |
| 5 | 126 |
| 6 | 472 |
| 7 | 1765 |
| 8 | 6878 |
| 9 | 26812 |
| 10 | 107028 |
| 11 | 428929 |
| 12 | 1740321 |
| 13 | 7098405 |
| 14 | 29176482 |
| 15 | 120454790 |
| 16 | 500030927 |
| 17 | 2083449191 |
| 18 | 8715752041 |
| 19 | 36576288141 |
| 20 | 153968912861 |
| 21 | 649844829206 |
| 22 | 2749607363057 |
| 23 | 11659719519993 |
| 24 | 49545446311575 |
| 25 | 210926363580093 |
| 26 | 899529315714847 |
| 27 | 3842334024093159 |
[1,1,4,10,37,126,472,1765,6878,26812,107028, 428929,1740321,7098405,29176482,120454790, 500030927,2083449191,8715752041,36576288141, 153968912861,649844829206,2749607363057, 11659719519993,49545446311575,210926363580093, 899529315714847,3842334024093159] |