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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 25 |
| 4 | 90 |
| 5 | 312 |
| 6 | 1145 |
| 7 | 4186 |
| 8 | 15640 |
| 9 | 58681 |
| 10 | 222298 |
| 11 | 845848 |
| 12 | 3235385 |
| 13 | 12418650 |
| 14 | 47827992 |
| 15 | 184688185 |
| 16 | 714884186 |
| 17 | 2772776984 |
| 18 | 10774163001 |
| 19 | 41932100698 |
| 20 | 163430680600 |
| 21 | 637793652281 |
| 22 | 2491918144602 |
| 23 | 9746480252952 |
| 24 | 38157725306425 |
[1,2,8,25,90,312,1145,4186,15640,58681,222298, 845848,3235385,12418650,47827992,184688185, 714884186,2772776984,10774163001,41932100698, 163430680600,637793652281,2491918144602, 9746480252952,38157725306425] |