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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 9 |
| 3 | 25 |
| 4 | 241 |
| 5 | 1041 |
| 6 | 10681 |
| 7 | 60649 |
| 8 | 658785 |
| 9 | 4540321 |
| 10 | 51972841 |
| 11 | 415198521 |
| 12 | 4988808529 |
| 13 | 44847866545 |
| 14 | 563683953561 |
| 15 | 5586645006601 |
| 16 | 73228719433921 |
| 17 | 788319280278849 |
| 18 | 10747425123292105 |
| 19 | 124265401483446361 |
| 20 | 1757874020223846321 |
| 21 | 21640338257575264081 |
[1,1,9,25,241,1041,10681,60649,658785,4540321, 51972841,415198521,4988808529,44847866545, 563683953561,5586645006601,73228719433921, 788319280278849,10747425123292105, 124265401483446361,1757874020223846321, 21640338257575264081] |