What is the nth term of 1-5-9-13?

The sequence 1, 5, 9, 13 is an arithmetic sequence where the first term is 1 and the common difference is 4. The nth term can be found using the formula: ( a_n = a_1 + (n-1) \cdot d ), where ( a_1 ) is the first term and ( d ) is the common difference. Substituting the values, we get ( a_n = 1 + (n-1) \cdot 4 ). Simplifying this, the nth term is ( a_n = 4n - 3 ).