A391133 - OEIS

%I #14 Dec 02 2025 14:38:12

%S 1,0,0,1,8,68,454,1962

%N The number of connected planar graphs on n unlabeled vertices with connected planar complement.

%C This sequence is finite and there are no additional terms.

%o (SageMath)

%o def a(n):

%o     count = 0

%o     for G in graphs(n):

%o         C = G.complement()

%o         if G.is_planar() and G.is_connected() and C.is_planar() and C.is_connected():

%o             count += 1

%o     return count

%o for n in range(1, 10): print(a(n))

%Y Cf. A391132 (not necessarily connected).

%K nonn,fini,full

%O 1,5

%A _Jim Nastos_, Nov 30 2025