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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 10 |
| 5 | 21 |
| 6 | 44 |
| 7 | 101 |
| 8 | 250 |
| 9 | 629 |
| 10 | 1557 |
| 11 | 3784 |
| 12 | 9120 |
| 13 | 21992 |
| 14 | 53228 |
| 15 | 129177 |
| 16 | 313701 |
| 17 | 761403 |
| 18 | 1846804 |
| 19 | 4478044 |
| 20 | 10858285 |
| 21 | 26332515 |
| 22 | 63865592 |
| 23 | 154900529 |
| 24 | 375691009 |
| 25 | 911166977 |
| 26 | 2209835169 |
| 27 | 5359470121 |
| 28 | 12998281146 |
| 29 | 31524747503 |
| 30 | 76457088518 |
| 31 | 185431544730 |
[0,1,4,10,21,44,101,250,629,1557,3784,9120,21992, 53228,129177,313701,761403,1846804,4478044, 10858285,26332515,63865592,154900529,375691009, 911166977,2209835169,5359470121,12998281146, 31524747503,76457088518,185431544730] |