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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 7 |
| 4 | 135 |
| 5 | 5521 |
| 6 | 418711 |
| 7 | 52505552 |
| 8 | 10034306147 |
| 9 | 2768027299909 |
| 10 | 1055389479690007 |
| 11 | 536926409666609040 |
| 12 | 354534107755578318094 |
| 13 | 297045945287473702734584 |
| 14 | 309828094123717787726306772 |
| 15 | 395818917891236220205710173248 |
| 16 | 610789854576714911900411852031035 |
| 17 | 1124694852500570258500087576570621947 |
| 18 | 2445082865412664444306698277861664761891 |
[1,1,7,135,5521,418711,52505552,10034306147, 2768027299909,1055389479690007,536926409666609040, 354534107755578318094,297045945287473702734584, 309828094123717787726306772, 395818917891236220205710173248, 610789854576714911900411852031035, 1124694852500570258500087576570621947, 2445082865412664444306698277861664761891] |