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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 23 |
| 4 | 96 |
| 5 | 370 |
| 6 | 1582 |
| 7 | 6521 |
| 8 | 28643 |
| 9 | 122638 |
| 10 | 546792 |
| 11 | 2394446 |
| 12 | 10792173 |
| 13 | 48021728 |
| 14 | 218179960 |
| 15 | 981883990 |
| 16 | 4488678934 |
| 17 | 20373041373 |
| 18 | 93593834773 |
| 19 | 427623466487 |
| 20 | 1972421243699 |
| 21 | 9059494556338 |
| 22 | 41927367649728 |
| 23 | 193403822529562 |
| 24 | 897622038677730 |
| 25 | 4155362828482880 |
| 26 | 19333035594712891 |
| 27 | 89767486969505492 |
[1,2,7,23,96,370,1582,6521,28643,122638,546792, 2394446,10792173,48021728,218179960,981883990, 4488678934,20373041373,93593834773,427623466487, 1972421243699,9059494556338,41927367649728, 193403822529562,897622038677730,4155362828482880, 19333035594712891,89767486969505492] |