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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 17 |
| 4 | 128 |
| 5 | 1131 |
| 6 | 11070 |
| 7 | 116317 |
| 8 | 1287480 |
| 9 | 14829188 |
| 10 | 176250143 |
| 11 | 2148687567 |
| 12 | 26750057584 |
| 13 | 338939419026 |
| 14 | 4359422270652 |
| 15 | 56799490825125 |
| 16 | 748414965684808 |
| 17 | 9959308633462092 |
| 18 | 133694287642377756 |
| 19 | 1808762770097970724 |
| 20 | 24642635223262953600 |
| 21 | 337856475305856870275 |
[1,3,17,128,1131,11070,116317,1287480,14829188, 176250143,2148687567,26750057584,338939419026, 4359422270652,56799490825125,748414965684808, 9959308633462092,133694287642377756, 1808762770097970724,24642635223262953600, 337856475305856870275] |