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| n | a(n) |
|---|---|
| 1 | 50 |
| 2 | 250 |
| 3 | 1120 |
| 4 | 4670 |
| 5 | 18606 |
| 6 | 71710 |
| 7 | 270016 |
| 8 | 998834 |
| 9 | 3646406 |
| 10 | 13176346 |
| 11 | 47242048 |
| 12 | 168350870 |
| 13 | 597109486 |
| 14 | 2110060262 |
| 15 | 7435237264 |
| 16 | 26141362890 |
| 17 | 91751051238 |
| 18 | 321596169218 |
| 19 | 1126053324976 |
| 20 | 3939647403086 |
| 21 | 13774810332334 |
| 22 | 48139938720622 |
[50,250,1120,4670,18606,71710,270016,998834, 3646406,13176346,47242048,168350870,597109486, 2110060262,7435237264,26141362890,91751051238, 321596169218,1126053324976,3939647403086, 13774810332334,48139938720622] |