what is a general term for the set: {15,30,45,60,75,...}

Question

what is a general term for the set {15,30,45,60,75,...}

Answer 1

The set whose elements are multiples of 15. However, the set whose elements are multiples of 15 should contain the number 0 because 0 is a multiple of all numbers. You could say the set whose elements are positive multiples of 15.