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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 83 |
| 6 | 348 |
| 7 | 1499 |
| 8 | 6623 |
| 9 | 29805 |
| 10 | 136080 |
| 11 | 628537 |
| 12 | 2930993 |
| 13 | 13772875 |
| 14 | 65132877 |
| 15 | 309654749 |
| 16 | 1478735723 |
| 17 | 7088395315 |
| 18 | 34089167561 |
| 19 | 164401035964 |
| 20 | 794796779867 |
| 21 | 3850714202599 |
| 22 | 18691819399273 |
| 23 | 90885695919131 |
| 24 | 442583806441116 |
| 25 | 2158167279743194 |
| 26 | 10536761139563128 |
| 27 | 51500580609300347 |
[1,1,2,6,21,83,348,1499,6623,29805,136080,628537, 2930993,13772875,65132877,309654749,1478735723, 7088395315,34089167561,164401035964,794796779867, 3850714202599,18691819399273,90885695919131, 442583806441116,2158167279743194, 10536761139563128,51500580609300347] |