Sunday, October 7, 2012

Sylvester's Stamp Puzzle

The stamp puzzle for denominations 4 c and 7 c is illustrate above. The lattice points on the plane z=4x+7y are shown in black. The integer(x,y) pairs are shown in red for given z. The yellow plane (z=17) has no integer solutions in this octant. It has integer solution (-1,3). Note 28 has solutions (7,0) and (0,4) and 56: (14,0),(0,8), (7,4)...