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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 26 |
| 3 | 90 |
| 4 | 310 |
| 5 | 1082 |
| 6 | 3844 |
| 7 | 13892 |
| 8 | 50950 |
| 9 | 189130 |
| 10 | 708876 |
| 11 | 2677452 |
| 12 | 10175356 |
| 13 | 38863780 |
| 14 | 149045960 |
| 15 | 573559240 |
| 16 | 2213551430 |
| 17 | 8563950250 |
| 18 | 33203854460 |
| 19 | 128978378620 |
| 20 | 501839077460 |
| 21 | 1955475615820 |
| 22 | 7629823818680 |
| 23 | 29805375256120 |
| 24 | 116558646378140 |
| 25 | 456270710243332 |
[1,7,26,90,310,1082,3844,13892,50950,189130, 708876,2677452,10175356,38863780,149045960, 573559240,2213551430,8563950250,33203854460, 128978378620,501839077460,1955475615820, 7629823818680,29805375256120,116558646378140, 456270710243332] |