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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 23 |
| 5 | 80 |
| 6 | 290 |
| 7 | 1010 |
| 8 | 3521 |
| 9 | 12934 |
| 10 | 48498 |
| 11 | 180020 |
| 12 | 666648 |
| 13 | 2512214 |
| 14 | 9569120 |
| 15 | 36408682 |
| 16 | 138417669 |
| 17 | 529685612 |
| 18 | 2038304708 |
| 19 | 7852427512 |
| 20 | 30259337658 |
| 21 | 116937868076 |
| 22 | 453269554872 |
| 23 | 1759337897040 |
| 24 | 6833437297968 |
| 25 | 26582114114294 |
[1,3,8,23,80,290,1010,3521,12934,48498,180020, 666648,2512214,9569120,36408682,138417669, 529685612,2038304708,7852427512,30259337658, 116937868076,453269554872,1759337897040, 6833437297968,26582114114294] |