A certain computer program generates a sequence of numbers P1,P2,........Pn by the rules P1=1,P2=1, and for n>or =(equal) to 3,Pn=Pn-1+2 Pn-2.which of the following equals P5?
A)10.
B)11.
C)14.
D)15.
E)17
p1 =1 p2 = 1
p3 = p2 + 2 p1 = 1 + 2 = 3
p4 = p3 + 2p2 = 3+2= 5
p5 = p4 + 2p3 =5 + 6 = 11