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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 26 |
| 4 | 102 |
| 5 | 420 |
| 6 | 1762 |
| 7 | 7546 |
| 8 | 32776 |
| 9 | 143740 |
| 10 | 636509 |
| 11 | 2837470 |
| 12 | 12723564 |
| 13 | 57356783 |
| 14 | 259622346 |
| 15 | 1179671953 |
| 16 | 5378030204 |
| 17 | 24587733520 |
| 18 | 112709464907 |
| 19 | 517854785497 |
| 20 | 2384306458458 |
| 21 | 10998978703826 |
| 22 | 50826959867930 |
| 23 | 235249720011487 |
| 24 | 1090445475090001 |
| 25 | 5061348100981751 |
| 26 | 23522089805096353 |
| 27 | 109444564002516165 |
[1,2,7,26,102,420,1762,7546,32776,143740,636509, 2837470,12723564,57356783,259622346,1179671953, 5378030204,24587733520,112709464907,517854785497, 2384306458458,10998978703826,50826959867930, 235249720011487,1090445475090001,5061348100981751, 23522089805096353,109444564002516165] |