cp's OEIS Frontend

A360871 Number of unlabeled nonseparable (or 2-connected) multigraphs with n edges and degree >= 3 at each node, loops allowed.

%I A360871 #7 Feb 25 2023 18:07:12
%S A360871 0,0,2,4,9,20,44,113,329,1044,3622,13544,53596,223084,969158
%N A360871 Number of unlabeled nonseparable (or 2-connected) multigraphs with n edges and degree >= 3 at each node, loops allowed.
%C A360871 A single-edge is considered to be nonseparable here.
%e A360871 The a(3) = 2 multigraphs are:
%e A360871   - a triple edge;
%e A360871   - a single edge with a loop at each vertex.
%Y A360871 Row sums of A360870.
%Y A360871 Cf. A002935, A360863, A360867.
%K A360871 nonn,more
%O A360871 1,3
%A A360871 _Andrew Howroyd_, Feb 25 2023