login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Number of unlabeled connected multigraphs with n edges, no cut-points and degree >= 3 at each node, loops allowed.
1

%I #8 Feb 27 2023 11:22:45

%S 0,1,3,5,10,21,45,114,330,1045,3623,13545,53597,223085,969159

%N Number of unlabeled connected multigraphs with n edges, no cut-points and degree >= 3 at each node, loops allowed.

%F a(n) = A360871(n) + 1 for n > 1.

%e The a(3) = 3 multigraphs are:

%e - a single vertex with 3 loops;

%e - a triple edge;

%e - a single edge with a loop at each vertex.

%Y Cf. A002935, A360863, A360867, A360871.

%Y Row sums of A360870.

%K nonn,more

%O 1,3

%A _Andrew Howroyd_, Feb 27 2023