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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 21 |
| 3 | 421 |
| 4 | 13421 |
| 5 | 323421 |
| 6 | 12023421 |
| 7 | 241023421 |
| 8 | 10321023421 |
| 9 | 211421023421 |
| 10 | 4233421023421 |
| 11 | 140223421023421 |
| 12 | 3310023421023421 |
| 13 | 121201023421023421 |
| 14 | 2424021023421023421 |
| 15 | 104030421023421023421 |
| 16 | 2131113421023421023421 |
| 17 | 43122323421023421023421 |
| 18 | 1413002023421023421023421 |
[0,1,21,421,13421,323421,12023421,241023421, 10321023421,211421023421,4233421023421, 140223421023421,3310023421023421, 121201023421023421,2424021023421023421, 104030421023421023421,2131113421023421023421, 43122323421023421023421,1413002023421023421023421] |