Find the sum of sequence `1,3,5,7,.....` upto `20` terms.

Find the sum of the sequence 7,77,777,7777... to n terms.

Find the sum to n term of the A.P.1,3,5,7.....

Sum of the series 1+3+7+15+....... upto n terms.

Find the sum of the following series: ( i ) 1,3,5,7... upto 12 terms.

Find sum of series 1.2+2.3+3.4.... upto n terms

Find the number of common terms in the following sequences : 1, 5, 9, ... to 100 terms and 4, 7, 10, ... to 100 terms.

Find the sum of the series 1+3x+5x^(2)+7x^(3)+...... upto n terms.

Find the number of common terms in the following sequences : 3, 7, 11, ... to 100 terms and 2, 5, 8, ... to 100 terms.

Find the sum to n terms of the sequence 1,2,4,7,11,16, .........