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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 8 |
| 3 | 21 |
| 4 | 56 |
| 5 | 150 |
| 6 | 408 |
| 7 | 1099 |
| 8 | 2984 |
| 9 | 8109 |
| 10 | 22030 |
| 11 | 59884 |
| 12 | 162756 |
| 13 | 442416 |
| 14 | 1202614 |
| 15 | 3269025 |
| 16 | 8886112 |
| 17 | 24154960 |
| 18 | 65659986 |
| 19 | 178482314 |
| 20 | 485165200 |
| 21 | 1318815750 |
| 22 | 3584912848 |
| 23 | 9744803461 |
| 24 | 26489122152 |
| 25 | 72004899350 |
| 26 | 195729609452 |
[3,8,21,56,150,408,1099,2984,8109,22030,59884, 162756,442416,1202614,3269025,8886112,24154960, 65659986,178482314,485165200,1318815750, 3584912848,9744803461,26489122152,72004899350, 195729609452] |