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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 75 |
| 6 | 259 |
| 7 | 862 |
| 8 | 2808 |
| 9 | 9090 |
| 10 | 29489 |
| 11 | 96076 |
| 12 | 314011 |
| 13 | 1027749 |
| 14 | 3364559 |
| 15 | 11012071 |
| 16 | 36033146 |
| 17 | 117891838 |
| 18 | 385711145 |
| 19 | 1261999184 |
| 20 | 4129291969 |
| 21 | 13511534900 |
| 22 | 44211907218 |
| 23 | 144668866862 |
| 24 | 473380823897 |
| 25 | 1548980397627 |
| 26 | 5068520414694 |
| 27 | 16585048409912 |
| 28 | 54269098388346 |
| 29 | 177577820365484 |
[1,1,2,6,21,75,259,862,2808,9090,29489,96076, 314011,1027749,3364559,11012071,36033146, 117891838,385711145,1261999184,4129291969, 13511534900,44211907218,144668866862,473380823897, 1548980397627,5068520414694,16585048409912, 54269098388346,177577820365484] |