Reading Code in 8 Ways to Output 8 Numbers
J, 3 * 3 = 9

1[2
+2+
2+2


Executing all directions:

       ". '1[2+2+2+2','2+2+2+1[2','1+2[2+2+2','2+2[2+1+2','2+2+2+2[1','2[1+2+2+2','2+2+2[2+1',:'2+1+2[2+2'
1 7 3 4 8 2 6 5


Explanation:


In J execution goes from right to left and there is no operator precedence.
The [ (left) takes the left side of its two operand so it essentially cancels the whole right side of our expression e.g. 1+2[2+2+2 becomes 1+2[6 and then 1+2.
The left expressions are additions with a total of 1, 2, 3 and 4 operands. There are two of each n-operand expressions one with the number 1 and one with only 2s. The additions with 1 generate the odd numbers and the others generate the even ones.