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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 4 |
| 2 | 9 |
| 3 | 21 |
| 4 | 55 |
| 5 | 155 |
| 6 | 407 |
| 7 | 1099 |
| 8 | 2981 |
| 9 | 8105 |
| 10 | 22033 |
| 11 | 59881 |
| 12 | 162757 |
| 13 | 442417 |
| 14 | 1202611 |
| 15 | 3269021 |
| 16 | 8886117 |
| 17 | 24154953 |
| 18 | 65659981 |
| 19 | 178482301 |
| 20 | 485165203 |
| 21 | 1318815739 |
| 22 | 3584912849 |
| 23 | 9744803447 |
| 24 | 26489122131 |
| 25 | 72004899341 |
| 26 | 195729609431 |
[4,4,9,21,55,155,407,1099,2981,8105,22033,59881, 162757,442417,1202611,3269021,8886117,24154953, 65659981,178482301,485165203,1318815739, 3584912849,9744803447,26489122131,72004899341, 195729609431] |