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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 6 |
| 3 | 26 |
| 4 | 90 |
| 5 | 340 |
| 6 | 1194 |
| 7 | 4424 |
| 8 | 15766 |
| 9 | 57754 |
| 10 | 207500 |
| 11 | 755822 |
| 12 | 2726558 |
| 13 | 9903504 |
| 14 | 35798370 |
| 15 | 129844290 |
| 16 | 469823642 |
| 17 | 1702892772 |
| 18 | 6164774336 |
| 19 | 22336556588 |
| 20 | 80882514452 |
| 21 | 293006418302 |
| 22 | 1061132591102 |
| 23 | 3843739599044 |
| 24 | 13921096670132 |
[2,6,26,90,340,1194,4424,15766,57754,207500, 755822,2726558,9903504,35798370,129844290, 469823642,1702892772,6164774336,22336556588, 80882514452,293006418302,1061132591102, 3843739599044,13921096670132] |