L(N) denotes the Nth
Lucas Number.
Find the first three digits of L(2016)
http://mathworld.wolfram.com/LucasNumber.html
gives a nifty formula
L_n=[phi^n]
for n>=2 where phi is the golden ratio and [x] denotes the nearest integer function.
Raising the golden ratio to the 2106 power is too large for my calculator, but its common logarithm isn't.
2016log(phi)=421.3190827
Raising 10 to this power allows us to write in scientific notation:
2.084888069x10^421
So the answer is 208
Edited on November 7, 2016, 9:28 am

Posted by Jer
on 20161107 09:25:13 