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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 13 |
| 2 | 99 |
| 3 | 727 |
| 4 | 5391 |
| 5 | 40543 |
| 6 | 308799 |
| 7 | 2377087 |
| 8 | 18456831 |
| 9 | 144295423 |
| 10 | 1134207999 |
| 11 | 8952731647 |
| 12 | 70896259071 |
| 13 | 562816507903 |
| 14 | 4476410675199 |
| 15 | 35654557073407 |
| 16 | 284296086618111 |
| 17 | 2268726473129983 |
| 18 | 18115958466150399 |
| 19 | 144724547815866367 |
[1,13,99,727,5391,40543,308799,2377087,18456831, 144295423,1134207999,8952731647,70896259071, 562816507903,4476410675199,35654557073407, 284296086618111,2268726473129983, 18115958466150399,144724547815866367] |