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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 28 |
| 5 | 77 |
| 6 | 326 |
| 7 | 1028 |
| 8 | 4508 |
| 9 | 15255 |
| 10 | 68632 |
| 11 | 243837 |
| 12 | 1114866 |
| 13 | 4107946 |
| 14 | 19004015 |
| 15 | 71988788 |
| 16 | 336043828 |
| 17 | 1301048142 |
| 18 | 6116392715 |
| 19 | 24103744170 |
| 20 | 113963361244 |
| 21 | 455754834422 |
| 22 | 2164963692051 |
| 23 | 8765929019818 |
| 24 | 41804416460392 |
| 25 | 171069967405773 |
| 26 | 818553601362454 |
| 27 | 3380530240851678 |
| 28 | 16222030587174635 |
[1,1,3,7,28,77,326,1028,4508,15255,68632,243837, 1114866,4107946,19004015,71988788,336043828, 1301048142,6116392715,24103744170,113963361244, 455754834422,2164963692051,8765929019818, 41804416460392,171069967405773,818553601362454, 3380530240851678,16222030587174635] |