$$A095983$$
Number of biconnected labeled graphs on n nodes.
$$0, 0, 1, 10, 253, 11968, 1047613$$
$0\ 0$
$1\ 0$
$2\ 1$
$3\ 10$
$4\ 253$
$5\ 11968$
$6\ 1047613$
My enumeration with free turbo pascal gives the following result :
$3\ 1$
$4\ 10$
$5\ 238$
$6\ 11368$
$7\ 1014888$
I do not know why the numbers do not coincide. It seems that OEIS produced a shift of the numbers, but even after the correction the numbers do not coincide. Perhaps the problem has to do with the formulation "on n nodes" instead of "with n nodes". I counted the 2-vertex-connected undirected labeled graphs, which should be the same as biconnected graphs. My graphs were undirected, could it be that the graphs in OEIS are directed ?
It would be great if someone would at least check the case $n=5$, so that I know if I made a mistake in my program.