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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 18 |
| 3 | 270 |
| 4 | 5936 |
| 5 | 173330 |
| 6 | 6335772 |
| 7 | 278724362 |
| 8 | 14350790064 |
| 9 | 847007698338 |
| 10 | 56397332340020 |
| 11 | 4182866692785242 |
| 12 | 342022887565717800 |
| 13 | 30570009715185100082 |
| 14 | 2965368922693150575084 |
| 15 | 310276298423966343555690 |
| 16 | 34834957115496822249510752 |
| 17 | 4177193847524372747798263106 |
[1,2,18,270,5936,173330,6335772,278724362, 14350790064,847007698338,56397332340020, 4182866692785242,342022887565717800, 30570009715185100082,2965368922693150575084, 310276298423966343555690, 34834957115496822249510752, 4177193847524372747798263106] |