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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 3 |
| 3 | 48 |
| 4 | 675 |
| 5 | 9408 |
| 6 | 131043 |
| 7 | 1825200 |
| 8 | 25421763 |
| 9 | 354079488 |
| 10 | 4931691075 |
| 11 | 68689595568 |
| 12 | 956722646883 |
| 13 | 13325427460800 |
| 14 | 185599261804323 |
| 15 | 2585064237799728 |
| 16 | 36005300067391875 |
| 17 | 501489136705686528 |
| 18 | 6984842613812219523 |
| 19 | 97286307456665386800 |
| 20 | 1355023461779503195683 |
[0,3,48,675,9408,131043,1825200,25421763, 354079488,4931691075,68689595568,956722646883, 13325427460800,185599261804323,2585064237799728, 36005300067391875,501489136705686528, 6984842613812219523,97286307456665386800, 1355023461779503195683] |