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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 1 |
| 3 | 5 |
| 4 | 2 |
| 5 | 15 |
| 6 | 7 |
| 7 | 68 |
| 8 | 23 |
| 9 | 370 |
| 10 | 104 |
| 11 | 2649 |
| 12 | 571 |
| 13 | 25209 |
| 14 | 4176 |
| 15 | 313503 |
| 16 | 39827 |
| 17 | 5212881 |
| 18 | 500254 |
| 19 | 114569731 |
| 20 | 8348616 |
[1,2,1,5,2,15,7,68,23,370,104,2649,571,25209,4176, 313503,39827,5212881,500254,114569731,8348616] |