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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 31 |
| 3 | 209 |
| 4 | 1429 |
| 5 | 9791 |
| 6 | 67105 |
| 7 | 459941 |
| 8 | 3152479 |
| 9 | 21607409 |
| 10 | 148099381 |
| 11 | 1015088255 |
| 12 | 6957518401 |
| 13 | 47687540549 |
| 14 | 326855265439 |
| 15 | 2240299317521 |
| 16 | 15355239957205 |
| 17 | 105246380382911 |
| 18 | 721369422723169 |
| 19 | 4944339578679269 |
| 20 | 33889007628031711 |
| 21 | 232278713817542705 |
[1,5,31,209,1429,9791,67105,459941,3152479, 21607409,148099381,1015088255,6957518401, 47687540549,326855265439,2240299317521, 15355239957205,105246380382911,721369422723169, 4944339578679269,33889007628031711, 232278713817542705] |