Find the 13th term of arithmetic sequence whose common difference is d=7 and whose first term is a1=1.

You can find a specific term of an arithmetic sequence with the formula an = a1 + (n - 1) d.

a13 = 1 + (13 - 1) (7)

a13 = 1 + (12) (7)

a13 = 1 + 84

a13 = 85

The 13th term of this arithmetic sequence is 85. I hope this answers your question.