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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 21 |
| 6 | 27 |
| 7 | 35 |
| 8 | 108 |
| 9 | 154 |
| 10 | 867 |
| 11 | 1776 |
| 12 | 2464 |
| 13 | 3873 |
| 14 | 4505 |
| 15 | 4683 |
| 16 | 5502 |
| 17 | 13974 |
| 18 | 15631 |
| 19 | 33053 |
| 20 | 34306 |
| 21 | 50494 |
| 22 | 60630 |
| 23 | 62327 |
| 24 | 92512 |
| 25 | 92868 |
[0,1,3,6,21,27,35,108,154,867,1776,2464,3873,4505, 4683,5502,13974,15631,33053,34306,50494,60630, 62327,92512,92868] |