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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 30 |
| 5 | 124 |
| 6 | 516 |
| 7 | 2232 |
| 8 | 9750 |
| 9 | 43400 |
| 10 | 195248 |
| 11 | 887784 |
| 12 | 4068740 |
| 13 | 18780048 |
| 14 | 87191964 |
| 15 | 406900992 |
| 16 | 1907343750 |
| 17 | 8975758272 |
| 18 | 42385503300 |
| 19 | 200773540296 |
| 20 | 953674218720 |
| 21 | 4541306267856 |
| 22 | 21674415838068 |
| 23 | 103660251783288 |
[1,2,8,30,124,516,2232,9750,43400,195248,887784, 4068740,18780048,87191964,406900992,1907343750, 8975758272,42385503300,200773540296,953674218720, 4541306267856,21674415838068,103660251783288] |