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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 20 |
| 3 | 21 |
| 4 | 310 |
| 5 | 311 |
| 6 | 4200 |
| 7 | 4201 |
| 8 | 4220 |
| 9 | 4221 |
| 10 | 53110 |
| 11 | 53111 |
| 12 | 642000 |
| 13 | 642001 |
| 14 | 642020 |
| 15 | 642021 |
| 16 | 642310 |
| 17 | 642311 |
| 18 | 7531200 |
| 19 | 7531201 |
| 20 | 7531220 |
| 21 | 7531221 |
| 22 | 86420110 |
| 23 | 86420111 |
| 24 | 86424000 |
| 25 | 86424001 |
| 26 | 86424020 |
| 27 | 86424021 |
| 28 | 86424310 |
| 29 | 86424311 |
[0,1,20,21,310,311,4200,4201,4220,4221,53110, 53111,642000,642001,642020,642021,642310,642311, 7531200,7531201,7531220,7531221,86420110,86420111, 86424000,86424001,86424020,86424021,86424310, 86424311] |