The pattern looks like this: 200, 700, 1700, 3200.

The formula for the n^th term appears to be t_n=t_n-1+500*(n-1)

t1 = 200

t2 = 200+500*1

t3 = 200+500*1+500*2

t4 = 200+500*1+500*2+500*3

t5 = 200+500*1+500*2+500*3+500*4

t6 = 200+500*1+500*2+500*3+500*4+500*5

t7 = 200+500*1+500*2+500*3+500*4+500*5+500*6

t8 = 200+500*1+500*2+500*3+500*4+500*5+500*6+500*7 = 14,200