Graph designs for the eight-edge five-vertex graphs

The existence of graph designs for the two nonisomorphic graphs on five vertices and eight edges is determined in the case of index one, with three possible exceptions in total. It is established that for the unique graph with vertex sequence (3, 3, 3, 3, 4), a graph design of order nn exists exactly when n≡0,1(mod16) and n≠16n≠16, with the possible exception of n=48n=48. For the unique graph with vertex sequence (2,3,3,4,4)(2,3,3,4,4), a graph design of order nn exists exactly when n≡0,1(mod16), with the possible exceptions of n∈{32,48}n∈{32,48}.