An Eulerian graph is a graph containing an Eulerian cycle. The numbers of Eulerian graphs with n = 1, 2, ... nodes are 1, 1, 2, 3, 7, 15, 52, 236, ... (OEIS A133736), the first few of which are illustrated above. The corresponding numbers of connected Eulerian graphs are 1, 0, 1, 1, 4, 8, 37, 184, 1782, ... (OEIS A003049; Robinson 1969; Liskovec 1972, p. 117), the first few of which are illustrated above.

Eulerian cycle | Hamiltonian graph | two-graph