series,Chain vertices n,Reachable ordered pairs Original closure,2,1 Original closure,4,6 Original closure,6,15 Original closure,8,28 Original closure,10,45 Original closure,12,66 Original closure,14,91 Original closure,16,120 Original closure,18,153 Original closure,20,190 Original closure,22,231 Original closure,24,276 Original closure,26,325 Original closure,28,378 Original closure,30,435 Original closure,32,496 Retracted cross-cut pairs,2,1 Retracted cross-cut pairs,4,4 Retracted cross-cut pairs,6,9 Retracted cross-cut pairs,8,16 Retracted cross-cut pairs,10,25 Retracted cross-cut pairs,12,36 Retracted cross-cut pairs,14,49 Retracted cross-cut pairs,16,64 Retracted cross-cut pairs,18,81 Retracted cross-cut pairs,20,100 Retracted cross-cut pairs,22,121 Retracted cross-cut pairs,24,144 Retracted cross-cut pairs,26,169 Retracted cross-cut pairs,28,196 Retracted cross-cut pairs,30,225 Retracted cross-cut pairs,32,256