Find f(5) for this sequence:

f(1) = 2 and f(2) = 3, f(n) = f(1) + f(2) + f(n - 1), for n 2.

f(5) = ______

Question

Find f(5) for this sequence:

f(1) = 2 and f(2) = 3, f(n) = f(1) + f(2) + f(n - 1), for n > 2.

f(5) = ______

anonymous · Answer

f(n) = f(1) + f(2) + f(n - 1)
put n=3
we find 
 f(3) =  f(1) + f(2) + f(3 - 1)
i.e. f(3) =  f(1) + f(2) + f(2)
i.e. f(3) =  2 + 2*3 = 8 

put n=4
we find 
 f(4) =  f(1) + f(2) + f(4 - 1)
i.e. f(4) =  f(1) + f(2) + f(3)
i.e. f(4) =  2 + 3 + 8=13

put n=5
we find 
 f(5) =  f(1) + f(2) + f(5 - 1)
i.e. f(5) =  f(1) + f(2) + f(4)
i.e. f(5) =  2 + 3 + 13=18

Thus 
f(5) =  18 is the required Answer.

anonymous · Answer

Thank you so much, can you answer another one like it?

anonymous · Answer

f(1) = 2 and f(2) = 3, f(n) = f(n - 1) + f(n - 2), for n > 2.

anonymous · Answer

@greenlegodude57 What do you want to find?