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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 21 |
| 2 | 4541 |
| 3 | 198765 |
| 4 | 3083569 |
| 5 | 27634481 |
| 6 | 164379601 |
| 7 | 759891589 |
| 8 | 2839094517 |
| 9 | 9183188589 |
| 10 | 26107328109 |
| 11 | 67602028569 |
| 12 | 160441685209 |
| 13 | 357086356401 |
| 14 | 746545031221 |
| 15 | 1487788785845 |
| 16 | 2829595966381 |
| 17 | 5188248484757 |
| 18 | 9170828884817 |
[1,21,4541,198765,3083569,27634481,164379601, 759891589,2839094517,9183188589,26107328109, 67602028569,160441685209,357086356401, 746545031221,1487788785845,2829595966381, 5188248484757,9170828884817] |