Question 578597
There are many choices for an arithmetic sequence.
I can make one with all irrational numbers:
{{{a[1]=pi}}}
{{{a[2]=pi+sqrt(3)}}}
{{{a[3]=pi+2sqrt(3)}}}
{{{a[n]=pi+(n-1)sqrt(3)}}}
Maybe you are thinking of the formulas for the sum of an arithmetic sequence and about the 2 in the denominator. Well, the numerator will contain a product of two consecutive integers, like (n-1)n that will be even too, because one of those two integers has to be even. So, if the terms were integer, the sum will be integer too.