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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 8 |
| 5 | 28 |
| 6 | 20 |
| 7 | 43 |
| 8 | 143 |
| 9 | 249 |
| 10 | 546 |
| 11 | 1223 |
| 12 | 2703 |
| 13 | 8107 |
| 14 | 18085 |
| 15 | 44013 |
| 16 | 114919 |
| 17 | 327712 |
| 18 | 800937 |
| 19 | 2146066 |
| 20 | 5827711 |
| 21 | 15923828 |
| 22 | 43886143 |
| 23 | 121888966 |
| 24 | 340209504 |
| 25 | 955859391 |
| 26 | 2700771322 |
| 27 | 7652412896 |
| 28 | 21784431688 |
| 29 | 62248194140 |
| 30 | 178463482459 |
[1,2,2,8,28,20,43,143,249,546,1223,2703,8107, 18085,44013,114919,327712,800937,2146066,5827711, 15923828,43886143,121888966,340209504,955859391, 2700771322,7652412896,21784431688,62248194140, 178463482459] |