Mathematics

Problem

Let

A = \{1, 6, 11, 16, \dots\}

and

B = \{9, 16, 23, 30, \dots\}

be the sets consisting of the first 2025 terms of two arithmetic progressions. Then

n(A \cup B)

is [April 4, 2025 (I)] (a) 3814 (b) 4027 (c) 3761 (d) 4003