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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 23 |
| 4 | 91 |
| 5 | 388 |
| 6 | 1694 |
| 7 | 7580 |
| 8 | 34503 |
| 9 | 158934 |
| 10 | 740085 |
| 11 | 3472317 |
| 12 | 16403905 |
| 13 | 77905795 |
| 14 | 371712658 |
| 15 | 1780389419 |
| 16 | 8555917907 |
| 17 | 41234933337 |
| 18 | 199226988229 |
| 19 | 964687115736 |
| 20 | 4680221420684 |
| 21 | 22745569097665 |
| 22 | 110712610892370 |
| 23 | 539635195986892 |
| 24 | 2633586470388434 |
| 25 | 12867337964191294 |
| 26 | 62933164318540727 |
| 27 | 308092885324546279 |
[1,2,6,23,91,388,1694,7580,34503,158934,740085, 3472317,16403905,77905795,371712658,1780389419, 8555917907,41234933337,199226988229,964687115736, 4680221420684,22745569097665,110712610892370, 539635195986892,2633586470388434, 12867337964191294,62933164318540727, 308092885324546279] |