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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 119 |
| 6 | 718 |
| 7 | 5034 |
| 8 | 40297 |
| 9 | 362761 |
| 10 | 3628082 |
| 11 | 39911766 |
| 12 | 478961303 |
| 13 | 6226658039 |
| 14 | 87174663118 |
| 15 | 1307634456234 |
| 16 | 20922310926697 |
| 17 | 355681201437961 |
| 18 | 6402286531064882 |
| 19 | 121643792774375766 |
| 20 | 2432881085865713303 |
| 21 | 51090586490508002039 |
| 22 | 1123994325491076615118 |
[1,1,2,6,23,119,718,5034,40297,362761,3628082, 39911766,478961303,6226658039,87174663118, 1307634456234,20922310926697,355681201437961, 6402286531064882,121643792774375766, 2432881085865713303,51090586490508002039, 1123994325491076615118] |