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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 441 |
| 3 | 5852 |
| 4 | 55438 |
| 5 | 408222 |
| 6 | 2469182 |
| 7 | 12741432 |
| 8 | 57644194 |
| 9 | 233385140 |
| 10 | 859145920 |
| 11 | 2912085006 |
| 12 | 9181289736 |
| 13 | 27151590510 |
| 14 | 75840301088 |
| 15 | 201262238349 |
| 16 | 509972027785 |
| 17 | 1239109721281 |
| 18 | 2897739996141 |
| 19 | 6543276177902 |
| 20 | 14306873805792 |
| 21 | 30366198279340 |
[21,441,5852,55438,408222,2469182,12741432, 57644194,233385140,859145920,2912085006, 9181289736,27151590510,75840301088,201262238349, 509972027785,1239109721281,2897739996141, 6543276177902,14306873805792,30366198279340] |