Failed to parse (unknown function "\sp"): {\displaystyle {{{\left( -{E \ n \ {e \sp {\left( i \ a \ w \right)}}} -{E \ n \ {e \sp {\left( -{i \ a \ w} \right)}}} \right)} \ {\sin \left( {{a \ n}} \right)}} -{i \ E \ w \ {\cos \left( {{a \ n}} \right)} \ {e \sp {\left( i \ a \ w \right)}}}+{i \ E \ w \ {\cos \left( {{a \ n}} \right)} \ {e \sp {\left( -{i \ a \ w} \right)}}}} \over {{w \sp 2} -{n \sp 2}} \leqno(38) }