`1+(1+2)/2+(1+2+3)/3....`upto 20 terms is

The sum of the series: 1+(1)/(1+2)+(1)/(1+2+3)+...... upto 10 terms is :

Sum of first 20 terms of 3/1^2 + 5/(1^2 + 2^2) + 7/(1^2 + 2^2 + 3^2) +... upto 20 terms is :

Sum of first 20 terms of (3)/(1^(2))+(5)/(1^(2)+2^(2))+(7)/(1^(2)+2^(2)+3^(2))+... upto 20 terms is :

The sum of the series: 1+(1)/(1+2)+(1)/(1+2+3)+.... upto 10 terms,is :

Sum of series 1^(2)+(1^(2)+2^(2))+(1^(2)+2^(2)+3^(2))+... upto 22 terms is

Sum of -2,2(1)/(2),-3(1)/(8)... upto 6 terms is

The sum (3 xx 1^(3))/(1^(2)) + (5 xx (1^(3) + 2^(3)))/(1^(2) + 2^(2)) + (7 xx (1^(3) + 2^(3) + 3^(3)))/(1^(2) +2^(2) + 3^(2))... upto 10th term is

1,2,3…..sum of 20 term is

Sum of the series S=1+(1)/(2)(1+2)+(1)/(3)(1+2+3)+(1)/(4)(1+2+3+4)+ upto 20 terms is

If the sum 3/1^2+5/(1^2+2^2)+7/(1^2+2^2+3^2)+. . . + upto 20 terms is equal to k/21, then k is equal to