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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 10 |
| 5 | 22 |
| 6 | 64 |
| 7 | 147 |
| 8 | 409 |
| 9 | 1092 |
| 10 | 3253 |
| 11 | 8661 |
| 12 | 28585 |
| 13 | 83190 |
| 14 | 274001 |
| 15 | 912373 |
| 16 | 3366384 |
| 17 | 13253582 |
| 18 | 61533277 |
| 19 | 290493694 |
[1,1,2,4,10,22,64,147,409,1092,3253,8661,28585, 83190,274001,912373,3366384,13253582,61533277, 290493694] |