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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 6 |
| 4 | 16 |
| 5 | 42 |
| 6 | 101 |
| 7 | 280 |
| 8 | 657 |
| 9 | 1663 |
| 10 | 4107 |
| 11 | 10229 |
| 12 | 25333 |
| 13 | 63321 |
| 14 | 159135 |
| 15 | 399855 |
| 16 | 1014612 |
| 17 | 2582128 |
| 18 | 6592653 |
| 19 | 16898891 |
| 20 | 43435899 |
| 21 | 111985392 |
| 22 | 289453817 |
| 23 | 749973236 |
| 24 | 1947409123 |
| 25 | 5067034865 |
| 26 | 13208284732 |
| 27 | 34487824962 |
| 28 | 90192879037 |
[1,6,16,42,101,280,657,1663,4107,10229,25333, 63321,159135,399855,1014612,2582128,6592653, 16898891,43435899,111985392,289453817,749973236, 1947409123,5067034865,13208284732,34487824962, 90192879037] |