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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 3 |
| 3 | 14 |
| 4 | 74 |
| 5 | 377 |
| 6 | 1932 |
| 7 | 9888 |
| 8 | 50619 |
| 9 | 259118 |
| 10 | 1326434 |
| 11 | 6790049 |
| 12 | 34758444 |
| 13 | 177929400 |
| 14 | 910825347 |
| 15 | 4662539246 |
| 16 | 23867662778 |
| 17 | 122179202441 |
| 18 | 625438596492 |
| 19 | 3201636859344 |
| 20 | 16389264488331 |
| 21 | 83897082108014 |
| 22 | 429471401309714 |
[0,3,14,74,377,1932,9888,50619,259118,1326434, 6790049,34758444,177929400,910825347,4662539246, 23867662778,122179202441,625438596492, 3201636859344,16389264488331,83897082108014, 429471401309714] |