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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 26 |
| 4 | 126 |
| 5 | 602 |
| 6 | 2766 |
| 7 | 12266 |
| 8 | 52926 |
| 9 | 223802 |
| 10 | 932526 |
| 11 | 3844106 |
| 12 | 15722526 |
| 13 | 63936602 |
| 14 | 258902286 |
| 15 | 1045109546 |
| 16 | 4209004926 |
| 17 | 16921851002 |
| 18 | 67945160046 |
| 19 | 272554432586 |
| 20 | 1092540156126 |
| 21 | 4377129999002 |
| 22 | 17529432313806 |
| 23 | 70180474597226 |
[1,2,6,26,126,602,2766,12266,52926,223802,932526, 3844106,15722526,63936602,258902286,1045109546, 4209004926,16921851002,67945160046,272554432586, 1092540156126,4377129999002,17529432313806, 70180474597226] |