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%I #48 Jan 02 2023 12:30:46
%S 0,0,0,0,1,3,21,345,13429,1109105,162318088,39460518399
%N Number of simple unlabeled n-node graphs of connectivity 4.
%H Brendan McKay, <a href="http://list.seqfan.eu/oldermail/seqfan/2015-July/015022.html">confusion over k-connected graphs</a>, posting to Sequence Fans Mailing List, Jul 08 2015.
%H Jens M. Schmidt, <a href="/A324088/a324088.html">Data files in graph6 format</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/k-ConnectedGraph.html">k-Connected Graph</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/VertexConnectivity.html">Vertex Connectivity</a>
%F a(n) = A086216(n) - A086217(n). - _Andrey Zabolotskiy_, Nov 20 2017
%e The a(6) = 3 exactly-4-connected 6-node graphs are the complete graph K_6 with 1, 2, or 3 non-adjacent edges removed.
%Y Cf. A052442, A052443, A052444, A086216, A086217, A259862.
%K nonn,more,hard
%O 1,6
%A _Eric W. Weisstein_
%E Partially edited by _N. J. A. Sloane_, Jul 08 2015 at the suggestion of _Brendan McKay_
%E a(8)-a(11) copied from A259862 by _Andrey Zabolotskiy_, Nov 20 2017
%E a(4)-a(5) corrected by _Andrew Howroyd_, Aug 28 2019
%E a(12) from _Sean A. Irvine_, Dec 12 2021
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