The problem statement is ambiguous... no real question is stated but we assume that the word statement is intended to be translated into an algebraic expression. 
"13 more than the square of a number n' translates to '13+n^2'

'the difference between the number and 19 can be interpreted as either 'n-19' or '19-n'

the algebraic expression may be '(13+n^2)+(n-19)'