Singular, one, three, five, seven, nine, eleven, thirteen, fifteen, seventeen, nineteen, twenty-one, twenty-three, twenty-five, twenty-seven, twenty-nine, thirty-one, thirty-three, thirty-five, thirty-seven, thirty-nine, forty-one, forty-three, forty-five, forty-seven, forty-nine, fifty-one, fifty-three

Singular number refers to the odd number in mathematics, as opposed to the double number in mathematics. The singular number can be represented by 2n plus 1. Even numbers are mathematically correct even numbers, which can be represented by numbers such as 2n, and even numbers should be divisible by 2.