2 3 6 7 July 8, 2019 16 32 64 128 2 3 6 7 8 2 3 6 7 in fraction 2 3 6 7 14 2 3 6 7 9 2 3 6 7 8 9 2 3 6 7 naphthalenetetracarboxylic dianhydride 2 3 * 6 7 * 4 5 2 3 6 7 11 2 3 6 7 12 2 3 6 7 1 2 3 6 7 4 2 3 6 7 5 2 3 6 7 10 2 3 6 7 tetramethylnonane
