a(n) = 2^(2*n+1) * (2*n+1)*n^(2*n).A217971a(n) = 2^(2*n+1) * (2*n+1)*n^(2*n).Terms a(0) =24a(1) =2560a(2) =653184a(3) =301989888a(4) =220000000000External referencesoeis: A217971