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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 30 |
| 5 | 109 |
| 6 | 401 |
| 7 | 1495 |
| 8 | 5623 |
| 9 | 21289 |
| 10 | 81034 |
| 11 | 309817 |
| 12 | 1188932 |
| 13 | 4576980 |
| 14 | 17667647 |
| 15 | 68359881 |
| 16 | 265045494 |
| 17 | 1029512644 |
| 18 | 4005417845 |
| 19 | 15606129991 |
| 20 | 60885118375 |
| 21 | 237816401610 |
| 22 | 929909358659 |
| 23 | 3639712494186 |
| 24 | 14258889345834 |
| 25 | 55906875628333 |
| 26 | 219370377887309 |
| 27 | 861389105627213 |
| 28 | 3384600499000626 |
[0,1,2,8,30,109,401,1495,5623,21289,81034,309817, 1188932,4576980,17667647,68359881,265045494, 1029512644,4005417845,15606129991,60885118375, 237816401610,929909358659,3639712494186, 14258889345834,55906875628333,219370377887309, 861389105627213,3384600499000626] |