Repeated-root constacyclic codes of length $2\ell^mp^n$
  For any different odd primes $\ell$ and $p$, structure of constacyclic codes of length $2\ell^mp^n$ over a finite field $\mathbb F_q$ of characteritic $p$ and their duals is established in term of their generator polynomials. Among other results, all linear complimentary dual and self-dual constacyclic codes of length $2\ell^mp^n$ over $\mathbb F_q$ are obtained. 
Bocong Chen, Hai Q. Dinh, Hongwei Liu
cs.IT math.IT