  The aim of this work is to investigate the F-index and F-coindex of the line
graphs of the cycle graphs, star graphs, tadpole graphs, wheel graphs and
ladder graphs using the subdivision concepts. F-index of the line graph of
subdivision graph of square grid graph, 2D-lattice, nanotube and nanotorus of
$TUC_{4}C_{8}[p, q]$ are also investigated here.
