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) = ______

Answer 1

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.

Answer 2

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

Answer 3

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

Answer 4

@greenlegodude57 What do you want to find?