V[x_,q_,n_]:=q((n(n+1))/(2((Cosh[x])^2)))

k[x_,q_,n_]:=(Sqrt[2(En-V[x,q,n])])

(Subscript[M, c])[x_,q_,n_,dx_]:={{(E^(I k[x,q,n]*dx)),0},{0,(E^(-I k[x,q,n]*dx))}}

(Subscript[M, s])[x_,q_,n_,dx_]:=0.5*{{1+((k[x,q,n])/(k[x+dx,q,n])),1-((k[x,q,n])/(k[x+dx,q,n]))},{1-((k[x,q,n])/(k[x+dx,q,n])),1+((k[x,q,n])/(k[x+dx,q,n]))}}

listmultiplier[list_,partitionwidth_:5]:=NestWhile[Dot@@@Partition[#,partitionwidth,partitionwidth,1,{}]&,list,Dimensions[#][[1]]>1&][[1]]

BigM[q_,n_,dx_]:=Reverse@Table[(Subscript[M, s])[x,q,n,dx].(Subscript[M, c])[x,q,n,dx],{x,-3,3,dx}]//N;

Mlist1=BigM[1,1,0.005];Mlist2=BigM[-1,1,0.005];

Plot[{1/(((ComplexExpand@Abs@listmultiplier[Mlist1,10][[2]][[2]]))^2),1/(((ComplexExpand@Abs@listmultiplier[Mlist2,10][[2]][[2]]))^2)},{En,0,1},PlotRange->All,PlotStyle->{Black,Red},PlotLegends->{"T∈(SubPlus[V])","T∈(SubMinus[V])"},AxesLabel->{"E","T"},PlotLabel->"T(E), for n = 1"]