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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 4 |
| 6 | 11 |
| 7 | 23 |
| 8 | 62 |
| 9 | 149 |
| 10 | 409 |
| 11 | 1066 |
| 12 | 2931 |
| 13 | 7981 |
| 14 | 22166 |
| 15 | 61508 |
| 16 | 172267 |
| 17 | 483088 |
| 18 | 1361475 |
| 19 | 3845139 |
| 20 | 10894630 |
[1,1,1,3,4,11,23,62,149,409,1066,2931,7981,22166, 61508,172267,483088,1361475,3845139,10894630] |