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| n | a(n) |
|---|---|
| -1 | 1 |
| 0 | 3 |
| 1 | 9 |
| 2 | 21 |
| 3 | 45 |
| 4 | 99 |
| 5 | 225 |
| 6 | 507 |
| 7 | 1101 |
| 8 | 2295 |
| 9 | 4653 |
| 10 | 9381 |
| 11 | 19221 |
| 12 | 40491 |
| 13 | 87453 |
| 14 | 191205 |
| 15 | 417117 |
| 16 | 898119 |
| 17 | 1897125 |
| 18 | 3922977 |
| 19 | 7945713 |
| 20 | 15800367 |
| 21 | 30960765 |
| 22 | 60068235 |
| 23 | 116058981 |
| 24 | 224778159 |
| 25 | 439342677 |
| 26 | 871864317 |
| 27 | 1764029985 |
| 28 | 3643978479 |
| 29 | 7672441101 |
| 30 | 16397598555 |
| 31 | 35377739037 |
[1,3,9,21,45,99,225,507,1101,2295,4653,9381,19221, 40491,87453,191205,417117,898119,1897125,3922977, 7945713,15800367,30960765,60068235,116058981, 224778159,439342677,871864317,1764029985, 3643978479,7672441101,16397598555,35377739037] |