pr ism , ▁, ▁although ▁it ▁can ' t ▁be ▁made ▁uniform . ▁ ▁An ▁ion ic ▁subgroup ▁is ▁[( 5 , 3 )+ , 2 ], ▁( ), ▁order ▁ 1 2 0 , ▁( D u ▁Val ▁# 4 9 ' ▁( I / C 1 ; I / C 1 )* , ▁Con way ▁+ 1 / 6 0 [ I x I ]. 2 1 ). ▁This ▁group ▁represents ▁the ▁construction ▁of ▁the ▁sn ub ▁d ode c ah ed ral ▁pr ism , ▁. ▁ ▁A ▁half ▁subgroup ▁is ▁[ 5 , 3 , 2 , 1 + ] ▁= ▁[ 5 , 3 , 1 ] ▁= ▁[ 5 , 3 ], ▁( ▁= ▁), ▁order ▁ 1 2 0 , ▁( D u ▁Val ▁# 4 9 " ▁( I / C 1 ; I / C 1 ) − *, ▁Con way ▁+ 1 / 6 0 [ I x I ]. 2 3 ). ▁It ▁is ▁called ▁the ▁ icos ah ed ral ▁py ram idal ▁group ▁and ▁is ▁the ▁ 3 D ▁ icos ah ed ral ▁group , ▁[ 5 , 3 ]. ▁ ▁A ▁regular ▁d ode c ah ed ral ▁py ram id ▁can ▁have ▁this ▁symmetry , ▁with ▁Sch lä fli ▁symbol : ▁(   ) ▁ ∨ ▁{ 5 , 3 }. ▁ ▁A ▁ch iral ▁half ▁subgroup ▁is ▁[( 5 , 3 )+ , 2 , 1 + ] ▁= ▁[ 5 , 3 , 1 ]+