If `sum_(r=1)^n t_r= (n(n+1)(n+2))/3 then sum _(r=1)^oo 1/t_r=`
(A) -1
(B) 1
(C) 0
(D) none of these

If sum_(r=1)^n t_r=n/8(n+1)(n+2)(n+3), then find sum_(r=1)^n1/(t_r)dot

If sum_(r=1)^n T_r=(3^n-1), then find the sum of sum_(r=1)^n1/(T_r) .

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

If a=sum_(r=1)^oo(1/r)^2, b=sum_(r=1)^oo1/((2r-1)^2), then a/b= (A) 5/4 (B) 4/5 (C) 3/4 (D) none of these

If Sigma_(r=1)^(n) T_r=n/8(n+1)(n+2)(n+3) then find Sigma_(r=1)^(n) 1/T_r

If C_r stands for .^nC_r and sum_(r=1)^n (r.C_r)/(C_(r-1)) =210 then n= (A) 19 (B) 20 (C) 21 (D) none of these

If sum_(r=1)^nt_r=sum_(k=1)^nsum_(j=1)^ksum_(i=1)^j2 , then sum_(r=1)^n1/t_r=

If sum _(r =1) ^(n ) T _(r) = (n +1) ( n +2) ( n +3) then find sum _( r =1) ^(n) (1)/(T _(r))

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 sum_(r=1)^n T_r=n(2n^2+9n+13), then find the sum sum_(r=1)^nsqrt(T_r)dot