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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 80 |
| 5 | 872 |
| 6 | 11928 |
| 7 | 195072 |
| 8 | 3702080 |
| 9 | 80065792 |
| 10 | 1950808000 |
| 11 | 53016791360 |
| 12 | 1587229842688 |
| 13 | 51619520360960 |
| 14 | 1808576831681536 |
| 15 | 68562454975587328 |
| 16 | 2830905156661645312 |
| 17 | 124395772159835529216 |
| 18 | 5504660984739184156672 |
| 19 | 250011277837808237105152 |
| 20 | 14799530615476409472303104 |
[1,2,10,80,872,11928,195072,3702080,80065792, 1950808000,53016791360,1587229842688, 51619520360960,1808576831681536,68562454975587328, 2830905156661645312,124395772159835529216, 5504660984739184156672,250011277837808237105152, 14799530615476409472303104] |