Domino question

[Richard Guy]

I'm not sure that I understand this, but
I observe that dominoes usually come in
sets of  n+2 choose 2, including blanks
(zeroes) and doubles, the commonest
being  n=6  28 dominoes

0:0 0:1 1:1 0:2 1:2 2:2 .... 6:6   R.

On Wed, 23 Aug 2006, David Wilson wrote:

> Imagine placing a set of dominoes with
numbers 1 through n (there would be
choose(n, 2) such dominoes, having each
possible pair of numbers). Let a region
be an edge-connected set of grid squares
(polyomino) covered by the same domino
number. In terms of n, what is the
smallest number of regions possible once
all dominoes have been placed?