A computer program produces a sequence a1, a2, a3, ... such that a1=a2=1 and ak=a(k-1)*3-1 for 2 < k < n for some n. If n=9, what is a6? Choose one.
A) 35	B) 37	C) 39	D) 41	E) 43
a1=1   a2=1   a3=1*3-1= 
<gadget id="calculator">1*3-1</gadget>
<output>2</output>
2   a4=2*3-1= 
<gadget id="calculator">2*3-1</gadget>
<output>5</output>
5   a5=5*3-1= 
<gadget id="calculator">5*3-1</gadget>
<output>14</output>
14   a6=14*3-1=42-1= 
<gadget id="calculator">42-1</gadget>
<output>41</output>
41   41
<result>D</result>
A computer program produces a sequence a1, a2, a3, ... such that a1=a2=1 and ak=a(k-1)*3-1 for 2 < k < n for some n. If n=9, what is a6?