“…When = 2, there are a lot of literatures on constacyclic codes over rings F p m [u]/ u 2 = F p m + uF p m for various prime p and positive integers m (see, e.g., [1], [2], [4], [8], [10], [12]- [14], [17], [18], [20], [31].) In particular, structure of and Hamming distance distibution of all constacyclic codes of length p s over F p m + uF p m were completely determined in [8], [15], [22]. When = 3, in 2015, [35] determined the structure of (δ + αu 2 )-constacyclic codes of length p s over F p m [u]/ u 3 = F p m +uF p m +u 2 F p m .…”