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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 441 |
| 3 | 2491 |
| 4 | 13494 |
| 5 | 58026 |
| 6 | 197256 |
| 7 | 683257 |
| 8 | 2037721 |
| 9 | 5952936 |
| 10 | 16732138 |
| 11 | 44859931 |
| 12 | 119159921 |
| 13 | 307712676 |
| 14 | 784050794 |
| 15 | 1976285122 |
| 16 | 4919758858 |
| 17 | 12172588913 |
| 18 | 29902600211 |
| 19 | 73076993300 |
| 20 | 177908921984 |
| 21 | 431510277616 |
| 22 | 1043914139326 |
[21,441,2491,13494,58026,197256,683257,2037721, 5952936,16732138,44859931,119159921,307712676, 784050794,1976285122,4919758858,12172588913, 29902600211,73076993300,177908921984,431510277616, 1043914139326] |