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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 21 |
| 5 | 53 |
| 6 | 132 |
| 7 | 323 |
| 8 | 783 |
| 9 | 1880 |
| 10 | 4485 |
| 11 | 10637 |
| 12 | 25116 |
| 13 | 59075 |
| 14 | 138519 |
| 15 | 323936 |
| 16 | 755877 |
| 17 | 1760453 |
| 18 | 4093620 |
| 19 | 9506051 |
| 20 | 22049055 |
| 21 | 51091496 |
| 22 | 118287237 |
| 23 | 273658877 |
| 24 | 632714892 |
| 25 | 1462080131 |
| 26 | 3377002023 |
| 27 | 7796796848 |
| 28 | 17994911781 |
| 29 | 41519520053 |
[1,3,8,21,53,132,323,783,1880,4485,10637,25116, 59075,138519,323936,755877,1760453,4093620, 9506051,22049055,51091496,118287237,273658877, 632714892,1462080131,3377002023,7796796848, 17994911781,41519520053] |