Sum to n terms the series `1+3+7+15+31+...`

Sum up to n terms the series

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

Sum to n terms of the series :1 + 2 (1 + (1)/(n)) + 3 (1 + (1)/(n )) ^(2) + ………

Sum to n terms of the series 1^(3) - (1.5)^(3) +2^(3)-(2.5)^(3) +…. is

Find the nth term and then the sum to n terms of the series 3.5 +4.7+ 5.9 +....

Find the nth term and the sum to n terms of the series 1.2+ 2.3 +3.4 + ...

Sum to n terms the series (3)/(1 ^(2) . 2 ^(2)) + (5)/( 2 ^(2) . 3 ^(2)) + (7)/( 3 ^(2) . 4 ^(2)) +.............

Sum to n terms the series : 7+77+777+...

Find the sum of the first n terms of the series : 3 + 7 + 13 +21 + 31 +.....

Find the sum of the first n terms of the series : 3 + 7 + 13 +21 + 31 +dot dot dot