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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 8 |
| 3 | 23 |
| 4 | 63 |
| 5 | 167 |
| 6 | 440 |
| 7 | 1154 |
| 8 | 3024 |
| 9 | 7919 |
| 10 | 20735 |
| 11 | 54287 |
| 12 | 142128 |
| 13 | 372098 |
| 14 | 974168 |
| 15 | 2550407 |
| 16 | 6677055 |
| 17 | 17480759 |
| 18 | 45765224 |
| 19 | 119814914 |
| 20 | 313679520 |
| 21 | 821223647 |
| 22 | 2149991423 |
| 23 | 5628750623 |
| 24 | 14736260448 |
| 25 | 38580030722 |
| 26 | 101003831720 |
[0,2,8,23,63,167,440,1154,3024,7919,20735,54287, 142128,372098,974168,2550407,6677055,17480759, 45765224,119814914,313679520,821223647,2149991423, 5628750623,14736260448,38580030722,101003831720] |