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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 12 |
| 4 | 38 |
| 5 | 114 |
| 6 | 400 |
| 7 | 1449 |
| 8 | 5046 |
| 9 | 19172 |
| 10 | 74305 |
| 11 | 279604 |
| 12 | 1113750 |
| 13 | 4496546 |
| 14 | 17740654 |
| 15 | 72906831 |
| 16 | 302544900 |
| 17 | 1232387061 |
| 18 | 5177998210 |
| 19 | 21916697255 |
| 20 | 91351341100 |
| 21 | 390218601347 |
| 22 | 1676532979278 |
| 23 | 7110199280273 |
| 24 | 30763793677041 |
| 25 | 133728879288601 |
| 26 | 574879647533236 |
| 27 | 2512912116732564 |
| 28 | 11026835136668849 |
[1,2,4,12,38,114,400,1449,5046,19172,74305,279604, 1113750,4496546,17740654,72906831,302544900, 1232387061,5177998210,21916697255,91351341100, 390218601347,1676532979278,7110199280273, 30763793677041,133728879288601,574879647533236, 2512912116732564,11026835136668849] |