
EXAMPLE

n = 1: singleton graph K_1 (1 graph).
n = 2: 2empty graph, path graph P_2 (2 graphs).
n = 3: 3empty graph, path graph P_3, triangle graph C_3 = K_3 (3 graphs).
n = 4: 4empty graph, claw graph K_{1,3}, diamond graph K_{1,1,2} = K_4e, P_4, square graph C_4, tetrahedral graph K_4 (6 graphs).
