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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 19 |
| 3 | 79 |
| 4 | 339 |
| 5 | 1431 |
| 6 | 6072 |
| 7 | 25707 |
| 8 | 108922 |
| 9 | 461362 |
| 10 | 1954426 |
| 11 | 8278978 |
| 12 | 35070483 |
| 13 | 148560678 |
| 14 | 629313573 |
| 15 | 2665814361 |
| 16 | 11292572005 |
| 17 | 47836100785 |
| 18 | 202636977730 |
| 19 | 858384007525 |
| 20 | 3636173014596 |
| 21 | 15403076054964 |
| 22 | 65248477252164 |
[1,4,19,79,339,1431,6072,25707,108922,461362, 1954426,8278978,35070483,148560678,629313573, 2665814361,11292572005,47836100785,202636977730, 858384007525,3636173014596,15403076054964, 65248477252164] |