Mathematics

An arithmetic progression is defined by a constant difference between consecutive terms—the key is checking whether you can write $a_n = a_1 + (n-1)d$ for some fixed $d$. For finiteness, count whether the list explicitly ends or continues indefinitely (often signaled by "$\dots$"). These two properties are independent: a sequence can be finite and arithmetic, infinite and arithmetic, or infinite and non-arithmetic.

An arithmetic progression is defined by a constant difference between consecutive terms—the key is checking whether you can write $a_n = a_1 + (n-1)d$ for some fixed $d$. For finiteness, count whether the list explicitly ends or continues indefinitely (often signaled by "$\dots$"). These two properties are independent: a sequence can be finite and arithmetic, infinite and arithmetic, or infinite and non-arithmetic.