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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 10 |
| 2 | 42 |
| 3 | 174 |
| 4 | 718 |
| 5 | 3014 |
| 6 | 12726 |
| 7 | 54054 |
| 8 | 230046 |
| 9 | 980402 |
| 10 | 4177266 |
| 11 | 17789230 |
| 12 | 75680138 |
| 13 | 321616186 |
| 14 | 1365165694 |
| 15 | 5788182178 |
| 16 | 24514575654 |
| 17 | 103720434558 |
| 18 | 438421398326 |
| 19 | 1851566492994 |
| 20 | 7813337317842 |
| 21 | 32946701361962 |
| 22 | 138832416613530 |
[2,10,42,174,718,3014,12726,54054,230046,980402, 4177266,17789230,75680138,321616186,1365165694, 5788182178,24514575654,103720434558,438421398326, 1851566492994,7813337317842,32946701361962, 138832416613530] |