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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 39 |
| 5 | 112 |
| 6 | 514 |
| 7 | 1664 |
| 8 | 7851 |
| 9 | 27382 |
| 10 | 131105 |
| 11 | 481129 |
| 12 | 2325552 |
| 13 | 8853388 |
| 14 | 43081144 |
| 15 | 168640035 |
| 16 | 824599205 |
| 17 | 3299204419 |
| 18 | 16190983750 |
| 19 | 65931058149 |
| 20 | 324475345942 |
| 21 | 1340598991785 |
| 22 | 6612464402576 |
| 23 | 27654162310720 |
| 24 | 136650279385596 |
| 25 | 577427106053159 |
| 26 | 2857535277900956 |
| 27 | 12182684785904000 |
| 28 | 60363307435355304 |
[1,1,4,9,39,112,514,1664,7851,27382,131105,481129, 2325552,8853388,43081144,168640035,824599205, 3299204419,16190983750,65931058149,324475345942, 1340598991785,6612464402576,27654162310720, 136650279385596,577427106053159,2857535277900956, 12182684785904000,60363307435355304] |