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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 25 |
| 3 | 161 |
| 4 | 1250 |
| 5 | 9541 |
| 6 | 72715 |
| 7 | 554642 |
| 8 | 4229957 |
| 9 | 32260015 |
| 10 | 246033208 |
| 11 | 1876387859 |
| 12 | 14310392621 |
| 13 | 109139128192 |
| 14 | 832356568087 |
| 15 | 6348020808509 |
| 16 | 48413588270606 |
| 17 | 369229339341469 |
| 18 | 2815951262869471 |
| 19 | 21476033104508162 |
| 20 | 163788345340883417 |
[1,25,161,1250,9541,72715,554642,4229957,32260015, 246033208,1876387859,14310392621,109139128192, 832356568087,6348020808509,48413588270606, 369229339341469,2815951262869471, 21476033104508162,163788345340883417] |