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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 14 |
| 4 | 47 |
| 5 | 188 |
| 6 | 867 |
| 7 | 4460 |
| 8 | 25025 |
| 9 | 150890 |
| 10 | 967825 |
| 11 | 6554482 |
| 12 | 46600855 |
| 13 | 346228012 |
| 14 | 2677951311 |
| 15 | 21495038944 |
| 16 | 178565654041 |
| 17 | 1531692226714 |
| 18 | 13538763090277 |
| 19 | 123096619532030 |
| 20 | 1149440819867767 |
| 21 | 11007471611129700 |
[1,2,5,14,47,188,867,4460,25025,150890,967825, 6554482,46600855,346228012,2677951311,21495038944, 178565654041,1531692226714,13538763090277, 123096619532030,1149440819867767, 11007471611129700] |