Determine all nonnegative integers \(r\) such that it is possible for an infinite geometric sequence to contain exactly \(r\) terms that are integers. Prove your answer.
S = F/ [1 - R], where S = sum of infinite series, F = First term, R = Common ratio
S = 4 / [1 - 6/7]
S = 4 / (1/7)
S = 4 x 7
S = 28 =7 + 6 + 5 + 4 + 3 + 2 + 1 + 0
+158 
