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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 7 |
| 4 | 49 |
| 5 | 181 |
| 6 | 1201 |
| 7 | 16171 |
| 8 | 122977 |
| 9 | 971209 |
| 10 | 16788961 |
| 11 | 206578351 |
| 12 | 2094314641 |
| 13 | 40260673597 |
| 14 | 694617709969 |
| 15 | 9088535091091 |
| 16 | 187060085419201 |
| 17 | 4109646055718161 |
| 18 | 68029103349383617 |
| 19 | 1498126927153125079 |
| 20 | 39199612737165358321 |
| 21 | 799248202624341298501 |
[1,1,1,7,49,181,1201,16171,122977,971209,16788961, 206578351,2094314641,40260673597,694617709969, 9088535091091,187060085419201,4109646055718161, 68029103349383617,1498126927153125079, 39199612737165358321,799248202624341298501] |