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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 14 |
| 4 | 57 |
| 5 | 285 |
| 6 | 1712 |
| 7 | 11989 |
| 8 | 95919 |
| 9 | 863279 |
| 10 | 8632798 |
| 11 | 94960779 |
| 12 | 1139529348 |
| 13 | 14813881536 |
| 14 | 207394341513 |
| 15 | 3110915122698 |
| 16 | 49774641963168 |
| 17 | 846168913373870 |
| 18 | 15231040440729667 |
| 19 | 289389768373863686 |
| 20 | 5787795367477273728 |
[2,4,14,57,285,1712,11989,95919,863279,8632798, 94960779,1139529348,14813881536,207394341513, 3110915122698,49774641963168,846168913373870, 15231040440729667,289389768373863686, 5787795367477273728] |