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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 27 |
| 3 | 125 |
| 4 | 644 |
| 5 | 3643 |
| 6 | 21974 |
| 7 | 138395 |
| 8 | 898695 |
| 9 | 5970927 |
| 10 | 40386209 |
| 11 | 277127148 |
| 12 | 1924349756 |
| 13 | 13496536510 |
| 14 | 95467320600 |
| 15 | 680260392219 |
| 16 | 4878382821267 |
| 17 | 35182209381590 |
| 18 | 255000022472565 |
| 19 | 1856501085686340 |
| 20 | 13570366067586294 |
| 21 | 99554601986349471 |
| 22 | 732756800760507312 |
[1,6,27,125,644,3643,21974,138395,898695,5970927, 40386209,277127148,1924349756,13496536510, 95467320600,680260392219,4878382821267, 35182209381590,255000022472565,1856501085686340, 13570366067586294,99554601986349471, 732756800760507312] |