The table below shows values of and the expressions and .

 0  1  2  3  4  5  6 
 7  4  1  -2  -5  -8  -11 
 -5  -2  1  4  7  10  13 

For which values of in the table is:

(a) ? = help (numbers)

(b) ? = help (numbers)

(c) ? = help (numbers)

If there is more than one answer, enter your answers as a comma separated list. If there are no solutions, enter NONE.

You can earn partial credit on this problem.