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| n | a(n) |
|---|---|
| 0 | 3 |
| 1 | 6 |
| 2 | 18 |
| 3 | 57 |
| 4 | 186 |
| 5 | 621 |
| 6 | 2109 |
| 7 | 7251 |
| 8 | 25146 |
| 9 | 87726 |
| 10 | 307293 |
| 11 | 1079370 |
| 12 | 3798309 |
| 13 | 13382817 |
| 14 | 47191491 |
| 15 | 166501902 |
| 16 | 587670810 |
| 17 | 2074699233 |
| 18 | 7325660010 |
| 19 | 25869337773 |
| 20 | 91359785781 |
| 21 | 322660334739 |
| 22 | 1139593274178 |
| 23 | 4024976418198 |
| 24 | 14216179376325 |
| 25 | 50211881768346 |
| 26 | 177350652641349 |
[3,6,18,57,186,621,2109,7251,25146,87726,307293, 1079370,3798309,13382817,47191491,166501902, 587670810,2074699233,7325660010,25869337773, 91359785781,322660334739,1139593274178, 4024976418198,14216179376325,50211881768346, 177350652641349] |