|1 3|2 0|
Source: Henry Ernest Dudeny, 536 Curious Problems & Puzzles, #481.
In addition to the solutions for 2,3 and 4 here is what I've found for 5 and 6 dominos: 1 1 4 3 found sums 1 .. 9 1 3 3 2 found sums 1 .. 9 2 5 1 3 found sums 1 .. 9 4 1 2 6 found sums 1 .. 9 1 1 1 5 5 4 found sums 1 .. 17 1 1 4 4 4 3 found sums 1 .. 17 1 1 6 4 2 3 found sums 1 .. 17 1 1 6 4 3 2 found sums 1 .. 17 1 3 6 2 3 2 found sums 1 .. 17 3 2 1 6 4 4 found sums 1 .. 17 1 3 6 6 6 2 3 2 found sums 1 .. 29 1 1 1 5 6 6 6 4 5 4 found sums 1 .. 39 1 3 6 6 4 6 6 2 3 2 found sums 1 .. 39 2 5 2 6 6 6 6 4 1 3 found sums 1 .. 39 5 1 2 6 6 6 6 4 3 4 found sums 1 .. 39 1 1 1 5 6 6 5 6 6 4 5 4 found sums 1 .. 50 2 5 2 6 6 5 6 6 6 4 1 3 found sums 1 .. 50 Interestingly, there is a relation between some of the patterns: 1 1 4 3 found sums 1 .. 9 1 1 4 4 4 3 found sums 1 .. 17 1 1 1 5 5 4 found sums 1 .. 17 1 1 1 5 6 6 6 4 5 4 found sums 1 .. 39 1 1 1 5 6 6 5 6 6 4 5 4 found sums 1 .. 50 1 3 3 2 found sums 1 .. 9 1 3 6 2 3 2 found sums 1 .. 17 1 3 6 6 6 2 3 2 found sums 1 .. 29 1 3 6 6 4 6 6 2 3 2 found sums 1 .. 39 The sum of the dots on the domino added is also the increase between the maximum of the two patterns.