... combinatorics 3 (1996), #R16 17[GL1] R. L. Graham and B. D. Lubachevsky, Dense packings of equal disks in an equilateraltriangle: from2 2to3 4andbeyond,The Electronic Journ. of Combinatorics ... =2,3,4,5,6 ,and7 (n = 5, 10, 18,27, 39, and 52) and those packings (shown in Figs 2.9, 2.2, 2.5, and 2.8) are, indeed, optimal,except the case of n =10: proved[GMPW]forn = 5, 10, 18 and conjectured ... the right and three alternating rows at the top withone rattler at the top right corner. In each of the three additional rows and the three additionalcolumns, most disks are not touching each...