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| n | a(n) |
|---|---|
| 0 | 15 |
| 1 | 31 |
| 2 | 70 |
| 3 | 172 |
| 4 | 457 |
| 5 | 2295 |
| 6 | 12347 |
| 7 | 70843 |
| 8 | 431636 |
| 9 | 2781372 |
| 10 | 18885177 |
| 11 | 134670425 |
| 12 | 1005626319 |
| 13 | 7842880313 |
| 14 | 63733789544 |
| 15 | 538521313772 |
| 16 | 4722239916109 |
| 17 | 42899823779887 |
| 18 | 403127907995427 |
| 19 | 3912789622898471 |
| 20 | 39175487045290456 |
| 21 | 404110470650751416 |
| 22 | 4290001467563698869 |
[15,31,70,172,457,2295,12347,70843,431636,2781372, 18885177,134670425,1005626319,7842880313, 63733789544,538521313772,4722239916109, 42899823779887,403127907995427,3912789622898471, 39175487045290456,404110470650751416, 4290001467563698869] |