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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 41 |
| 5 | 127 |
| 6 | 395 |
| 7 | 1232 |
| 8 | 3842 |
| 9 | 11977 |
| 10 | 37336 |
| 11 | 116392 |
| 12 | 362846 |
| 13 | 1131150 |
| 14 | 3526285 |
| 15 | 10992961 |
| 16 | 34269838 |
| 17 | 106833983 |
| 18 | 333047961 |
| 19 | 1038255251 |
| 20 | 3236692893 |
| 21 | 10090178578 |
| 22 | 31455472326 |
| 23 | 98060379357 |
| 24 | 305696824386 |
| 25 | 952989872706 |
| 26 | 2970883650186 |
| 27 | 9261535631926 |
| 28 | 28872232090283 |
[1,1,4,13,41,127,395,1232,3842,11977,37336,116392, 362846,1131150,3526285,10992961,34269838, 106833983,333047961,1038255251,3236692893, 10090178578,31455472326,98060379357,305696824386, 952989872706,2970883650186,9261535631926, 28872232090283] |