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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 30 |
| 4 | 158 |
| 5 | 846 |
| 6 | 4446 |
| 7 | 22734 |
| 8 | 113310 |
| 9 | 552654 |
| 10 | 2647390 |
| 11 | 12492366 |
| 12 | 58202526 |
| 13 | 268228430 |
| 14 | 1224529758 |
| 15 | 5544352206 |
| 16 | 24921415326 |
| 17 | 111297979854 |
| 18 | 494186360670 |
| 19 | 2182903872334 |
| 20 | 9596971862430 |
| 21 | 42012203555406 |
| 22 | 183197641092446 |
[1,6,30,158,846,4446,22734,113310,552654,2647390, 12492366,58202526,268228430,1224529758,5544352206, 24921415326,111297979854,494186360670, 2182903872334,9596971862430,42012203555406, 183197641092446] |