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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 50 |
| 5 | 382 |
| 6 | 3434 |
| 7 | 35694 |
| 8 | 421682 |
| 9 | 5582158 |
| 10 | 81860978 |
| 11 | 1317457646 |
| 12 | 23087951666 |
| 13 | 437673142510 |
| 14 | 8924179990322 |
| 15 | 194763818998638 |
| 16 | 4530072136715954 |
| 17 | 111870258525352174 |
| 18 | 2923319958390174770 |
| 19 | 80590596894930389102 |
| 20 | 2337567736223817582002 |
| 21 | 71162943130933082039278 |
[1,1,2,8,50,382,3434,35694,421682,5582158, 81860978,1317457646,23087951666,437673142510, 8924179990322,194763818998638,4530072136715954, 111870258525352174,2923319958390174770, 80590596894930389102,2337567736223817582002, 71162943130933082039278] |