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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 6 |
| 3 | 9 |
| 4 | 20 |
| 5 | 43 |
| 6 | 94 |
| 7 | 213 |
| 8 | 456 |
| 9 | 1003 |
| 10 | 2146 |
| 11 | 4625 |
| 12 | 9852 |
| 13 | 20983 |
| 14 | 44438 |
| 15 | 93917 |
| 16 | 197808 |
| 17 | 415683 |
| 18 | 871370 |
| 19 | 1822889 |
| 20 | 3805924 |
| 21 | 7932303 |
| 22 | 16505342 |
| 23 | 34292341 |
| 24 | 71147800 |
| 25 | 147422043 |
| 26 | 305096754 |
| 27 | 630699073 |
| 28 | 1302409036 |
| 29 | 2686840103 |
| 30 | 5537724006 |
[2,6,9,20,43,94,213,456,1003,2146,4625,9852,20983, 44438,93917,197808,415683,871370,1822889,3805924, 7932303,16505342,34292341,71147800,147422043, 305096754,630699073,1302409036,2686840103, 5537724006] |