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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 4 |
| 2 | 5 |
| 3 | 9 |
| 4 | 21 |
| 5 | 53 |
| 6 | 133 |
| 7 | 325 |
| 8 | 773 |
| 9 | 1797 |
| 10 | 4101 |
| 11 | 9221 |
| 12 | 20485 |
| 13 | 45061 |
| 14 | 98309 |
| 15 | 212997 |
| 16 | 458757 |
| 17 | 983045 |
| 18 | 2097157 |
| 19 | 4456453 |
| 20 | 9437189 |
| 21 | 19922949 |
| 22 | 41943045 |
| 23 | 88080389 |
| 24 | 184549381 |
| 25 | 385875973 |
| 26 | 805306373 |
| 27 | 1677721605 |
| 28 | 3489660933 |
| 29 | 7247757317 |
[4,4,5,9,21,53,133,325,773,1797,4101,9221,20485, 45061,98309,212997,458757,983045,2097157,4456453, 9437189,19922949,41943045,88080389,184549381, 385875973,805306373,1677721605,3489660933, 7247757317] |