x { subtract i C subtract a series of numbers starting from 1 C e.g. subtract 10 gives: C 1 -2 -3 -4 -5 -6 -7 -8 -9 -10 C evaluated in left to right order C stored in n a { -I(i) n { 1, a[1+I(i-1)] 'the series is ',NJ n x { +/ n