tolong caranya...........

2,3,6,11,18
B1 = 1,3,5,7
B2 = 2,2,2

2a = 2
a = 1

3a + b = 1
3x1 + b = 1
b = 1-3 = -2

a+b+c = 2
1-2 + c = 2
-1 + c = 2
c = 2+1 = 3

Un = n² - 2n +3
U6 = 6² - 2x6 +3 = 27
U7 = 7² - 2x7 +3 = 38
U8 = 8² - 2x8 +3 = 51

3 suku berikutnya = 27,38,51