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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 22 |
| 5 | 46 |
| 6 | 109 |
| 7 | 237 |
| 8 | 571 |
| 9 | 1362 |
| 10 | 3459 |
| 11 | 8881 |
| 12 | 23698 |
| 13 | 63846 |
| 14 | 175489 |
| 15 | 485941 |
| 16 | 1359240 |
| 17 | 3821170 |
| 18 | 10803787 |
| 19 | 30654681 |
| 20 | 87295726 |
| 21 | 249262766 |
| 22 | 713583861 |
| 23 | 2047210813 |
| 24 | 5885081941 |
| 25 | 16947632202 |
| 26 | 48885431563 |
| 27 | 141220349049 |
[1,4,9,22,46,109,237,571,1362,3459,8881,23698, 63846,175489,485941,1359240,3821170,10803787, 30654681,87295726,249262766,713583861,2047210813, 5885081941,16947632202,48885431563,141220349049] |