To get the 2nd term, add 7 to the first term: 4 + 7 = 11
To get the 3rd term, add 7 to the second term: 11 + 7 = 18
Put another way, add 7 twice to the first term: 4 + 2*7 = 18
Similarly, get the 4th term by adding 7 to third term, or add 7 three times to the first term: 18 + 7 = 25, or 4 + 3*7 = 25.
Following the pattern, the n-th term of the sequence is obtained by adding n - 1 copies of 7 to the first term. So the 55th term is 4 + 54*7 = 382
