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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 19 |
| 3 | 48 |
| 4 | 645 |
| 5 | 5346 |
| 6 | 9989 |
| 7 | 423680 |
| 8 | 4936673 |
| 9 | 22863284 |
| 10 | 717864203 |
| 11 | 10398234146 |
| 12 | 14778845999 |
| 13 | 2318706892436 |
| 14 | 41349958502663 |
| 15 | 67290481692176 |
| 16 | 1273710986008283 |
| 17 | 21639017114636720 |
| 18 | 1870679510063123381 |
[1,4,19,48,645,5346,9989,423680,4936673,22863284, 717864203,10398234146,14778845999,2318706892436, 41349958502663,67290481692176,1273710986008283, 21639017114636720,1870679510063123381] |