The number of substrings (of all length inclusive) that can be formed from a character string of length $$n$$ is

If A and B are real symmetric matrices of size n x n. Then, which one of the following is true?

The number of distinct simple graph with upto three nodes is

In a compact single dimensional array representation for lower triangular matrices (i.e., all the elements above the diagonal are zero) of size $$n$$ $$x$$ $$n$$, non-zero elements (i.e., elements of the lower triangle) of each row are stored one after another, starting from the first row, the index of the $${\left( {i,\,j} \right)^{th}}$$ element of the lower triangular matrix in this new representation is