Dominoes are small rectangular tiles with dots called spots or pips embossed at both halves of the tiles. A standard "double-six" domino set has 28 tiles: one for each of the unordered pair of integers from (0,0) to (6,6). In general, a "double-n" domino set would consist of domino tiles for each unordered pair of integers from (0,0) to (n,n). Determine all values of n for which one constructs a ring made up of all the tiles in a double-n domino set. For example, here is a double-three set of dominoes. Each of the 10 dominoes would need to be placed in one of the locations in the ring so that halves of the same number of dots touched