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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 23 |
| 3 | 165 |
| 4 | 1383 |
| 5 | 13083 |
| 6 | 136863 |
| 7 | 1562715 |
| 8 | 19301319 |
| 9 | 256191363 |
| 10 | 3636036783 |
| 11 | 54956529675 |
| 12 | 881578601559 |
| 13 | 14964805041363 |
| 14 | 268105552191423 |
| 15 | 5057384615702235 |
| 16 | 100224731537223399 |
| 17 | 2082402995330965923 |
[1,4,23,165,1383,13083,136863,1562715,19301319, 256191363,3636036783,54956529675,881578601559, 14964805041363,268105552191423,5057384615702235, 100224731537223399,2082402995330965923] |