If `f(n)=2sum_(r=1)^(n-1)f(r),(n!=1),(n in N)` and `f(1)=1,` then `sum_(i=1)^(m) f(i)` is equal to

sum_(i=1)^(n) sum_(i=1)^(n) i is equal to

sum_(r=1)^n r (n-r +1) is equal to :

If S_(r)= sum_(r=1)^(n)T_(1)=n(n+1)(n+2)(n+3) then sum_(r=1)^(10) 1/(T_(r)) is equal to

If I(r)=r(r^2-1) , then sum_(r=2)^n 1/(I(r)) is equal to

Let sum_(r=1)^(n) r^(6)=f(n)," then "sum_(n=1)^(n) (2r-1)^(6) is equal to

If S_(n)=sum_(r=1)^(n) a_(r)=(1)/(6)n(2n^(2)+9n+13) , then sum_(r=1)^(n)sqrt(a_(r)) equals

If sum_(r=1)^n I(r)=(3^n -1) , then sum_(r=1)^n 1/(I(r)) is equal to :

For each positive integer n , let f(n+1)=n(-1)^(n+1)-2f(n) and f(1)=(2010)dot Then sum_(k=1)^(2009)f(K) is equal to 335 (b) 336 (c) 331 (d) 333

(sum_(r=1)^n r^4)/(sum_(r=1)^n r^2) is equal to

f(1)=1 and f(n)=2sum_(r=1)^(n-1) f (r) . Then sum_(n=1)^mf(n) is equal to (A) 3^m-1 (B) 3^m (C) 3^(m-1) (D)none of these