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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 882 |
| 3 | 1724 |
| 4 | 9940 |
| 5 | 67169 |
| 6 | 461894 |
| 7 | 3162172 |
| 8 | 21906411 |
| 9 | 152100304 |
| 10 | 1053377463 |
| 11 | 7321279936 |
| 12 | 50893161901 |
| 13 | 353396805989 |
| 14 | 2456759583794 |
| 15 | 17078402117279 |
| 16 | 118676436051497 |
| 17 | 824965798194515 |
| 18 | 5734649466128312 |
| 19 | 39857755473341719 |
[21,882,1724,9940,67169,461894,3162172,21906411, 152100304,1053377463,7321279936,50893161901, 353396805989,2456759583794,17078402117279, 118676436051497,824965798194515,5734649466128312, 39857755473341719] |