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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 50 |
| 6 | 181 |
| 7 | 714 |
| 8 | 2780 |
| 9 | 11046 |
| 10 | 43895 |
| 11 | 175274 |
| 12 | 699875 |
| 13 | 2798250 |
| 14 | 11188191 |
| 15 | 44747380 |
| 16 | 178970560 |
| 17 | 715860650 |
| 18 | 2863365834 |
| 19 | 11453377194 |
| 20 | 45813202675 |
| 21 | 183252461532 |
| 22 | 733008625151 |
| 23 | 2932033104554 |
| 24 | 11728127521060 |
| 25 | 46912504507000 |
| 26 | 187649998452735 |
| 27 | 750599971438464 |
[1,1,4,13,50,181,714,2780,11046,43895,175274, 699875,2798250,11188191,44747380,178970560, 715860650,2863365834,11453377194,45813202675, 183252461532,733008625151,2932033104554, 11728127521060,46912504507000,187649998452735, 750599971438464] |