What is the explicit rule of the sequence 3 5 7 9?

The explicit rule for the sequence 3, 5, 7, 9 can be expressed as ( a_n = 2n + 1 ), where ( n ) starts from 1. In this formula, ( a_n ) represents the nth term of the sequence. The sequence increases by 2 for each subsequent term, starting from 3. Thus, for ( n = 1, 2, 3, 4 ), the terms are 3, 5, 7, and 9, respectively.