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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 26 |
| 4 | 106 |
| 5 | 438 |
| 6 | 1886 |
| 7 | 8208 |
| 8 | 36645 |
| 9 | 164838 |
| 10 | 749978 |
| 11 | 3436717 |
| 12 | 15865958 |
| 13 | 73717234 |
| 14 | 344237449 |
| 15 | 1614232355 |
| 16 | 7599086216 |
| 17 | 35897479082 |
| 18 | 170135432788 |
| 19 | 808558437606 |
| 20 | 3851956705719 |
| 21 | 18391549249968 |
| 22 | 87996068206656 |
| 23 | 421846643489797 |
| 24 | 2025805986376666 |
| 25 | 9743584249035559 |
| 26 | 46932362767850800 |
| 27 | 226373652767896536 |
[1,2,7,26,106,438,1886,8208,36645,164838,749978, 3436717,15865958,73717234,344237449,1614232355, 7599086216,35897479082,170135432788,808558437606, 3851956705719,18391549249968,87996068206656, 421846643489797,2025805986376666,9743584249035559, 46932362767850800,226373652767896536] |