2 quads

[ignatus]

imagine each dozen consist of three horizontal lines: once column 1 or 3 has been hit 2 times in a row in one dozen two quads are placed in the 2 unhit columns in that particular dozen.

negative progression 2 quads: 1,1,1,1,2,2,3,4,5,6,8,10,13,17,22,28,36,46,59,76

played successfully on Eurogrand, but more testing is needed...