text: The formula for finding the nth term of an arithmetic sequence is\n\nan = a1 + (n - 1)d\n\nYou need the spacing, d:\n\n113 = 2 + (38 - 1)d\n111 = 37d\nd = 3\n\nThe formula for finding the sum of the sequence is\n\nS = n[2a1 + (n - 1)d] / 2\n= 38[2(2) + (38 - 1)3] /2\n= 38(4 + 111)/2\n= 38(115)/2\n= 2185