The Clar number of a fullerene graph with n vertices is bounded above by ⌊n/6⌋ − 2 and this bound has been improved to ⌊n/6⌋ − 3 when n is congruent to 2 modulo 6. We can construct at least one fullerene graph attaining the upper bounds for every even number of vertices n ≥ 20 except n = 22 and n = 30.
@article{bwmeta1.element.doi-10_7151_dmgt_2013, author = {Yang Gao and Heping Zhang}, title = {Sharp Upper Bounds on the Clar Number of Fullerene Graphs}, journal = {Discussiones Mathematicae Graph Theory}, volume = {38}, year = {2018}, pages = {155-163}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.doi-10_7151_dmgt_2013} }
Yang Gao; Heping Zhang. Sharp Upper Bounds on the Clar Number of Fullerene Graphs. Discussiones Mathematicae Graph Theory, Tome 38 (2018) pp. 155-163. http://gdmltest.u-ga.fr/item/bwmeta1.element.doi-10_7151_dmgt_2013/