a(n) = 2 * ceiling(n*((n^2)!^(1/n))).

A165554

a(n) = 2 * ceiling(n*((n^2)!^(1/n))).

Terms

    a(0) =2a(1) =20a(2) =428a(3) =17110a(4) =1091766a(5) =101766250a(6) =13040248694

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