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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 41 |
| 5 | 150 |
| 6 | 568 |
| 7 | 2115 |
| 8 | 7974 |
| 9 | 30307 |
| 10 | 115063 |
| 11 | 436831 |
| 12 | 1659809 |
| 13 | 6306619 |
| 14 | 24210855 |
| 15 | 93152526 |
| 16 | 357925365 |
| 17 | 1384070472 |
| 18 | 5365825156 |
| 19 | 20791117843 |
| 20 | 80784911668 |
| 21 | 314369613909 |
| 22 | 1223297887923 |
| 23 | 4773716056341 |
| 24 | 18647712778338 |
[1,1,4,13,41,150,568,2115,7974,30307,115063, 436831,1659809,6306619,24210855,93152526, 357925365,1384070472,5365825156,20791117843, 80784911668,314369613909,1223297887923, 4773716056341,18647712778338] |