What is the value of (see below)?

Consider the sequence that starts with a_1 = 7a1=7 and a_2 = 8a2=8, with a_n = (1 + a_(n−1))/a_(n−2) an=1+an1an2for n ≥ 3n3. What is the value of a_2017a2017?

1 Answer
Mar 5, 2018

a_2017=8a2017=8

Explanation:

We know the following:
a_1=7a1=7
a_2=8a2=8
a_n=(1+a_(n-1))/a_(n-2)an=1+an1an2

So:
a_3=(1+8)/7=9/7a3=1+87=97
a_4=(1+9/7)/8=2/7a4=1+978=27
a_5=(1+2/7)/(9/7)=1a5=1+2797=1
a_6=(1+1)/(2/7)=7a6=1+127=7
a_7=(1+7)/1=8a7=1+71=8

a_n=[(5n+1,5n+2,5n+3,5n+4,5n),(7,8,9/7,2/7,1)],ninZZ

Since, 2017=5n+2, a_2017=8