Answer:
a1=6 a2=15 a3=33 a4=69 a5=141
Explanation:
an=2an-1+3
We should attempt n=2 to find the second term
a2=2a1+3= 2*6+3=15
n=3 to find the third term
a3=2a2+3= 2*15+3=33
n=4 to find the fourth term
a4=2a3+3=2*33+3=69
n=5 to find the fifth term
a5= 2a4+3=2*69+3= 141