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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 9 |
| 2 | 17 |
| 3 | 114 |
| 4 | 533 |
| 5 | 3406 |
| 6 | 20281 |
| 7 | 132987 |
| 8 | 868359 |
| 9 | 5880694 |
| 10 | 40168271 |
| 11 | 279254657 |
| 12 | 1959385953 |
| 13 | 13894772276 |
| 14 | 99289815837 |
| 15 | 714761301180 |
| 16 | 5176706895201 |
| 17 | 37701431645548 |
| 18 | 275906664244201 |
| 19 | 2028001454003211 |
| 20 | 14964925167434231 |
[1,9,17,114,533,3406,20281,132987,868359,5880694, 40168271,279254657,1959385953,13894772276, 99289815837,714761301180,5176706895201, 37701431645548,275906664244201,2028001454003211, 14964925167434231] |