3x^2 + 6x -2
Lets do some spot-checks:
7,22,43,70,103,142,187,238
1,2 ,3 ,4 ,5 ,6 ,7 , 8
where x=1, y=3 * x^2 + 6 * x -2 = 3+6-2 = 7
where x=4, y=3 * x^2 + 6 * x -2 = 3*16 + 6*4 -2 = 48 + 14 -2 = 70
where x=8, y=3 * x^2 + 6 * x -2 = 3*64 + 6*8 -2 = 192 + 48 -2 = 238
Looks Good !