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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 16 |
| 3 | 123 |
| 4 | 947 |
| 5 | 7326 |
| 6 | 56710 |
| 7 | 439078 |
| 8 | 3399722 |
| 9 | 26323903 |
| 10 | 203825456 |
| 11 | 1578217598 |
| 12 | 12220118582 |
| 13 | 94620225492 |
| 14 | 732643232114 |
| 15 | 5672847473255 |
| 16 | 43924787764759 |
| 17 | 340109088005893 |
| 18 | 2633460459021237 |
| 19 | 20390851741033347 |
| 20 | 157886112662767667 |
[2,16,123,947,7326,56710,439078,3399722,26323903, 203825456,1578217598,12220118582,94620225492, 732643232114,5672847473255,43924787764759, 340109088005893,2633460459021237, 20390851741033347,157886112662767667] |