Find the sum to n terms of the sequence 8, 88, 888, 8888,…

Find the sum to n terms of the sequence {a_n} , where a_n=5-6n, n in N .

Find the sum to n terms of the sequence : 1,-1,1,-1,........ ,(-1)^(n+1) , ..........

Find the sum of n terms of the following sequences: 8+88+888+……………..up to n terms.

Find the sum of the sequence -8, -5, -2 ,... 7

Find the sum of n terms of the AP 6,13,20.....

Find the sum of the products of the corresponding terms of the sequences 2, 4, 8, 16, 32 and 128, 32, 8,2, 1/2 .

Find the sum to n terms of the series whose nth term is n^(2) + 2^(n) .

Find the 21st and 42nd terms of the sequence defined by : t_n= {(0,if n is odd),(1, if n is even):} .

Find the first six terms of the sequence whose first term is 1 and whose (n+1)th term is obtained by adding n to the nth term.

Find the sum to n terms of the series given below whose nth terms is given by n(n+1)(n+4).