a(n) = (1/(n-1)!) * Product_{i=1..n-1} (2^n-2^i).

A377642

a(n) = (1/(n-1)!) * Product_{i=1..n-1} (2^n-2^i).

Terms

    a(0) =1a(1) =2a(2) =12a(3) =224a(4) =13440a(5) =2666496a(6) =1791885312

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