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| n | a(n) |
|---|---|
| 1 | 7 |
| 2 | 28 |
| 3 | 126 |
| 4 | 524 |
| 5 | 2229 |
| 6 | 9425 |
| 7 | 39905 |
| 8 | 168925 |
| 9 | 715072 |
| 10 | 3027049 |
| 11 | 12813931 |
| 12 | 54243509 |
| 13 | 229621433 |
| 14 | 972024617 |
| 15 | 4114736810 |
| 16 | 17418344167 |
| 17 | 73734658344 |
| 18 | 312130693269 |
| 19 | 1321299533915 |
| 20 | 5593273893746 |
| 21 | 23677229915913 |
| 22 | 100229530526756 |
[7,28,126,524,2229,9425,39905,168925,715072, 3027049,12813931,54243509,229621433,972024617, 4114736810,17418344167,73734658344,312130693269, 1321299533915,5593273893746,23677229915913, 100229530526756] |