The value of the nth term = 1 + 6n. Since 7 is the 1st term, not the starting point, you would do 7-6 to get the starting point, or the value at 0. Then just add 6 a certain amount of times depending on which term it is. For example, for the first term, 7, you would add 6 to 1 one time, because it’s the first term, and you would get 1 + (6*1) = 7. Plug in any other number and it works too
Hope this helps