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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 31 |
| 2 | 638 |
| 3 | 10982 |
| 4 | 171171 |
| 5 | 2506917 |
| 6 | 35201776 |
| 7 | 479688604 |
| 8 | 6392929061 |
| 9 | 83765551883 |
| 10 | 1083070611714 |
| 11 | 13855878102066 |
| 12 | 175736023769671 |
| 13 | 2213065674408529 |
| 14 | 27704146634051252 |
| 15 | 345076242383014568 |
| 16 | 4279844990866901001 |
| 17 | 52886642197647118455 |
| 18 | 651455131567317021190 |
[1,31,638,10982,171171,2506917,35201776,479688604, 6392929061,83765551883,1083070611714, 13855878102066,175736023769671,2213065674408529, 27704146634051252,345076242383014568, 4279844990866901001,52886642197647118455, 651455131567317021190] |