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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 3 |
| 3 | 9 |
| 4 | 37 |
| 5 | 192 |
| 6 | 932 |
| 7 | 4712 |
| 8 | 23795 |
| 9 | 120610 |
| 10 | 612315 |
| 11 | 3110338 |
| 12 | 15805917 |
| 13 | 80334285 |
| 14 | 408339140 |
| 15 | 2075677553 |
| 16 | 10551347780 |
| 17 | 53636527966 |
| 18 | 272656370832 |
| 19 | 1386027291338 |
| 20 | 7045770251219 |
| 21 | 35816690408937 |
| 22 | 182071750375772 |
| 23 | 925549713377018 |
[0,3,9,37,192,932,4712,23795,120610,612315, 3110338,15805917,80334285,408339140,2075677553, 10551347780,53636527966,272656370832, 1386027291338,7045770251219,35816690408937, 182071750375772,925549713377018] |