For the infinite sequence of numbers a1, a2, a3, ..., an, ..., for all n > 1, an = an−1an−1 + 4 if n is odd and an = an−1 if n is even. What is the value of a1a1 if a34 = 68?  Choose one:  A) 10  B) 11  C) 12  D) 13  E) 21
a34= 68 = a33 - 1= 
<gadget id="calculator">33 - 1</gadget>
<output>32</output>
a32 - 1 +4 ... and so on   So observing the trend,   a34= a1 +(32/2) * 4 - (34/2) * (-1)   [32/2 to get all the even n (from 32 to 2) and 34/2 to get all the odd n (from 33 to 1) including 33 and 1]   a1 = 68-64+17= 
<gadget id="calculator">68-64+17</gadget>
<output>21</output>
21   Hence, answer will be 21.
<result>E</result>
For the infinite sequence of numbers a1, a2, a3, ..., an, ..., for all n > 1, an = an−1an−1 + 4 if n is odd and an = an−1 if n is even. What is the value of a1a1 if a34 = 68?