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

Sum to n terms the series 1 + (1+ 2) + (1 + 2 + 3) + (1 + 2 + 3 + 4).......

Find the sum of the series 1/(1.2.3.4)+1/(2.3.4.5)+1/(3.4.5.6)+....... upto n terms.

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

The sum of series 1/(1-3.1^2+1^4)+2/(1-3.3^2+2^4)+3/(1-3.3^2+3^4)+......... up to 10 terms, is equal to

Sum of the series 1/(4. 1^2-1)+1/(4. 2^2-1)+1/(4. 3^2-1)+ upto infinite terms is a. 3/2 (2) 1/2 (3) 1 (4) infinite

The sum of n terms of the series : (1)/( 1.2.3.4) + ( 1)/( 2.3.4.5) + ( 1) / ( 3.4.5.6.)+"......." is :

Sum of n terms of the series 1/(1.2.3.4.)+1/(2.3.4.5) +1/(3.4.5.6)+....

Sum of n terms of the series 1/(1.2.3.4.)+1/(2.3.4.5) +1/(3.4.5.6)+....

The sum of the series (1)/(1.2)-(1)/(2.3)+(1)/(3.4)-(1)/(4.5)+... is