A set of all positive integers divided by 3 and 2 The answer is {X / x = 3K + 2, K ∈ n}, but why K ∈ n instead of X ∈ n? Is it OK to use x ∈ n? But when k = 0, it doesn't seem to meet the conditions

A set of all positive integers divided by 3 and 2 The answer is {X / x = 3K + 2, K ∈ n}, but why K ∈ n instead of X ∈ n? Is it OK to use x ∈ n? But when k = 0, it doesn't seem to meet the conditions

When k runs through the whole n, don't you just get the set you want? And for each k ∈ n, X is the element of the set you want, so this expression is completely mathematical language to express the set composed of all positive integers divided by 3 and 2!