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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 81 |
| 6 | 325 |
| 7 | 1348 |
| 8 | 5757 |
| 9 | 25140 |
| 10 | 111909 |
| 11 | 505288 |
| 12 | 2308464 |
| 13 | 10647067 |
| 14 | 49502830 |
| 15 | 231719158 |
| 16 | 1090976509 |
| 17 | 5162200449 |
| 18 | 24532023007 |
| 19 | 117023282850 |
| 20 | 560084216123 |
| 21 | 2688492219885 |
| 22 | 12938889468296 |
| 23 | 62416183429988 |
| 24 | 301720885613818 |
| 25 | 1461274383849004 |
| 26 | 7089220442457957 |
| 27 | 34445894200583415 |
[1,1,2,6,21,81,325,1348,5757,25140,111909,505288, 2308464,10647067,49502830,231719158,1090976509, 5162200449,24532023007,117023282850,560084216123, 2688492219885,12938889468296,62416183429988, 301720885613818,1461274383849004,7089220442457957, 34445894200583415] |