Please help me will mark you brainliest

Plzzz plzz maths ! quadratic sequences =an^2+bn 1) 1,6,15,28,45 2)5,18,39,68,105 3) 1,8,21,40,65 4) 7,24,51,88,135 5) -1,2,9,20,35

Precalculus question, image attached.

Iam at home. /: i am playing video games. translate the following statement into symbolic form.