Let the first term = a1 and the second term = a2
Note that the 3rd term is = a1 + a2
And the 4th term is = a1 + 2a2
And the 5th term is = 2a1 + 3a2
So....the normal Fibonacci Series is
Fib (n) 1 2 3 4 5
Term 1 1 2 3 5 etc
Then...in the above series....it appears that the nth term (after the second one ) is given by :
Fib (n -2 )*a1 + Fib (n - 1)*a2
So....the 16th term is
Fib (16 - 2) * a1 + Fib (16 - 1) * a2 =
FIb (14) *( -3) + Fib (15) * 9
Note..... Fib (11) = 89 Fib (12) = 144 Fib (13) = 233 Fib (14) = 377 Fib(15) = 610
So....the 16th term is
(377)* (-3) + 610 * 9 =
4359