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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 86 |
| 5 | 664 |
| 6 | 6136 |
| 7 | 66240 |
| 8 | 816672 |
| 9 | 11331552 |
| 10 | 174662304 |
| 11 | 2961774144 |
| 12 | 54785368128 |
| 13 | 1097882522112 |
| 14 | 23693117756928 |
| 15 | 547844658441216 |
| 16 | 13511950038494208 |
| 17 | 354086653712228352 |
| 18 | 9824794572366544896 |
| 19 | 287752569360558907392 |
| 20 | 8871374335098501292032 |
[1,1,3,14,86,664,6136,66240,816672,11331552, 174662304,2961774144,54785368128,1097882522112, 23693117756928,547844658441216,13511950038494208, 354086653712228352,9824794572366544896, 287752569360558907392,8871374335098501292032] |