a(n) = 2^(2^n) + 2^(2^(n+1)-1).A365310a(n) = 2^(2^n) + 2^(2^(n+1)-1).Terms a(0) =4a(1) =12a(2) =144a(3) =33024a(4) =2147549184External referencesoeis: A365310