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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 16 |
| 5 | 40 |
| 6 | 100 |
| 7 | 252 |
| 8 | 636 |
| 9 | 1604 |
| 10 | 4044 |
| 11 | 10196 |
| 12 | 25708 |
| 13 | 64820 |
| 14 | 163436 |
| 15 | 412084 |
| 16 | 1039020 |
| 17 | 2619764 |
| 18 | 6605420 |
| 19 | 16654772 |
| 20 | 41993004 |
| 21 | 105880308 |
| 22 | 266964460 |
| 23 | 673118772 |
| 24 | 1697188012 |
| 25 | 4279255412 |
| 26 | 10789627756 |
| 27 | 27204748468 |
| 28 | 68593500716 |
| 29 | 172950260724 |
| 30 | 436073277676 |
[1,1,2,6,16,40,100,252,636,1604,4044,10196,25708, 64820,163436,412084,1039020,2619764,6605420, 16654772,41993004,105880308,266964460,673118772, 1697188012,4279255412,10789627756,27204748468, 68593500716,172950260724,436073277676] |