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%I M1149 #46 Apr 06 2022 05:19:36
%S 1,2,4,8,18,44,117,351,1230,5069,25181,152045,1116403,9899865,
%T 104980369,1318017549,19427531763,333964672216,6660282066936
%N Number of squarefree graphs on n vertices.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H CombOS - Combinatorial Object Server, <a href="http://combos.org/nauty">Generate graphs</a>
%H Brendan McKay, <a href="/A006785/a006785.pdf">Emails to N. J. A. Sloane, 1991</a>
%H B. D. McKay, <a href="http://users.cecs.anu.edu.au/~bdm/papers/orderly.pdf">Isomorph-free exhaustive generation</a>, J Algorithms, 26 (1998) 306-324.
%H S. Uijlen, B. Westerbaan, <a href="http://arxiv.org/abs/1412.8544">A Kochen-Specker system has at least 22 vectors</a>, arXiv preprint arXiv:1412.8544 [cs.DM], 2014.
%H S. Uijlen and B. Westerbaan, <a href="https://doi.org/10.1007/s00354-016-0202-5">A Kochen-Specker System Has at Least 22 Vectors</a>, New Generation Computing, Vol. 34, No. 1-2 (2016), 3-23.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Square-FreeGraph.html">Square-Free Graph</a>
%H <a href="/index/Sq#square_free">Index entries for sequences of squarefree graphs</a>
%Y Cf. A000088, A077269 (connected), A345249 (labeled), A039751 (complement). Row sums of A300756.
%K nonn,more
%O 1,2
%A _N. J. A. Sloane_.
%E 2 more terms (from the McKay paper) from _Vladeta Jovovic_, May 17 2008
%E 2 more terms from _Brendan McKay_, Mar 11 2018