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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 50 |
| 5 | 268 |
| 6 | 3780 |
| 7 | 28872 |
| 8 | 438410 |
| 9 | 4087180 |
| 10 | 65365260 |
| 11 | 697738072 |
| 12 | 11624944660 |
| 13 | 137432369816 |
| 14 | 2371412517480 |
| 15 | 30441246407440 |
| 16 | 542177876315970 |
| 17 | 7460629909188796 |
| 18 | 136882304192481020 |
| 19 | 2001263659780301080 |
| 20 | 37777108180867675020 |
| 21 | 583057080531893501960 |
| 22 | 11314432259935102732856 |
| 23 | 183452721005994056356272 |
[1,2,4,50,268,3780,28872,438410,4087180,65365260, 697738072,11624944660,137432369816,2371412517480, 30441246407440,542177876315970,7460629909188796, 136882304192481020,2001263659780301080, 37777108180867675020,583057080531893501960, 11314432259935102732856,183452721005994056356272] |