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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 3 |
| 2 | 8 |
| 3 | 24 |
| 4 | 63 |
| 5 | 168 |
| 6 | 440 |
| 7 | 1155 |
| 8 | 3024 |
| 9 | 7920 |
| 10 | 20735 |
| 11 | 54288 |
| 12 | 142128 |
| 13 | 372099 |
| 14 | 974168 |
| 15 | 2550408 |
| 16 | 6677055 |
| 17 | 17480760 |
| 18 | 45765224 |
| 19 | 119814915 |
| 20 | 313679520 |
| 21 | 821223648 |
| 22 | 2149991423 |
| 23 | 5628750624 |
| 24 | 14736260448 |
| 25 | 38580030723 |
| 26 | 101003831720 |
[0,3,8,24,63,168,440,1155,3024,7920,20735,54288, 142128,372099,974168,2550408,6677055,17480760, 45765224,119814915,313679520,821223648,2149991423, 5628750624,14736260448,38580030723,101003831720] |