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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 11 |
| 3 | 71 |
| 4 | 450 |
| 5 | 2879 |
| 6 | 18365 |
| 7 | 117146 |
| 8 | 747252 |
| 9 | 4766519 |
| 10 | 30404411 |
| 11 | 193941921 |
| 12 | 1237105726 |
| 13 | 7891179813 |
| 14 | 50335810076 |
| 15 | 321079209472 |
| 16 | 2048081844697 |
| 17 | 13064188271417 |
| 18 | 83333102938721 |
| 19 | 531560469056352 |
| 20 | 3390687761515265 |
[1,11,71,450,2879,18365,117146,747252,4766519, 30404411,193941921,1237105726,7891179813, 50335810076,321079209472,2048081844697, 13064188271417,83333102938721,531560469056352, 3390687761515265] |