If f 1 0 f m n f m f n 4 9mn-1 M n 0 Then what is f

given f(1)=0
so, f(2)=f(1+1)=f(1)+f(1)+36*1*1-1=0+0+36-1=0
similarly, f(3)=f(1+2)=106, f(4)=f(2+2)=f(1+3)=213, f(6)=f(2+4)=535, f(7)=f(3+4)=750, f(13)=f(6+7)=2796
now, f(17)=f(4+13)=4880.
11 years agoHelpfull: Yes(10) No(2)

f(1)=0
f(2)=f(1+1)=f(1)+f(1)+4*9*1*1-1=35
similarly, f(4)=213, f(5)=248, f(9)=1180, f(8)=1001
therefore,
f(17)=f(9+8)= f(9)+f(8)+4*9*9*8-1 = 4772 ANS.
11 years agoHelpfull: Yes(4) No(4)
@Prasanjit singh- your method is also good but your calculation is totally wrong.
right answer is 4880 whether you can solve anyhow.
11 years agoHelpfull: Yes(2) No(1)
@deepak kumar - there is no braces mentioned in 4*9mn-1 thus, * sign must be given more precedence. Thus, i don't find any calculation mistake in my solution.
11 years agoHelpfull: Yes(1) No(0)
ANS IS 4880.
@prasnnjit your approach is nice
but f(9)=1288. there u made a mistake.
11 years agoHelpfull: Yes(0) No(0)

If f(1)=0, f(m+n)=f(m)+f(n)+4*9mn-1, M,n>0
Then what is f(17)=?