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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 8 |
| 5 | 20 |
| 6 | 42 |
| 7 | 102 |
| 8 | 250 |
| 9 | 610 |
| 10 | 1486 |
| 11 | 3710 |
| 12 | 9228 |
| 13 | 23050 |
| 14 | 57718 |
| 15 | 145288 |
| 16 | 365820 |
| 17 | 922194 |
| 18 | 2327914 |
| 19 | 5885800 |
| 20 | 14890796 |
| 21 | 37701452 |
| 22 | 95550472 |
| 23 | 242325118 |
| 24 | 614869792 |
| 25 | 1561228066 |
| 26 | 3966071764 |
| 27 | 10080113232 |
| 28 | 25630109268 |
| 29 | 65194419268 |
| 30 | 165890640468 |
[1,2,4,8,20,42,102,250,610,1486,3710,9228,23050, 57718,145288,365820,922194,2327914,5885800, 14890796,37701452,95550472,242325118,614869792, 1561228066,3966071764,10080113232,25630109268, 65194419268,165890640468] |