Repeated-root constacyclic codes of length 6lmpn.

Let $ \mathbb{F}_{q} $ be a finite field with character $ p $. In this paper, the multiplicative group $ \mathbb{F}_{q}^{*} = \mathbb{F}_{q}\setminus\{0\} $ is decomposed into a mutually disjoint union of $ \gcd(6l^mp^n,q-1) $ cosets over subgroup $ <\xi^{6l^mp^n}> $, where $ \xi $ is a primitive element of $ \mathbb{F}_{q} $. Based on the decomposition, the structure of constacyclic codes of length $ 6l^mp^n $ over finite field $ \mathbb{F}_{q} $ and their duals is established in terms of their generator polynomials, where $ p\neq{3} $ and $ l\neq{3} $ are distinct odd primes, $ m $ and $ n $ are positive integers. In addition, we determine the characterization and enumeration of all linear complementary dual(LCD) negacyclic codes and self-dual constacyclic codes of length $ 6l^mp^n $ over $ \mathbb{F}_{q} $. [ABSTRACT FROM AUTHOR]