%I M1224 #36 Aug 22 2022 11:12:18
%S 1,2,4,10,27,92,369,1807,10344,67659,491347,3894446,33278992,
%T 304256984,2960093835,30523315419,332524557107,3816805831381,
%U 46048851321131,582691924941142,7717878059859874,106806430860694984,1541683193805924288,23173865491070682522
%N Number of interval graphs on n unlabeled nodes.
%D P. J. Hanlon, personal communication.
%D R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1980.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H R. W. Robinson, <a href="/A005975/b005975.txt">Table of n, a(n) for n = 1..30</a>
%H Hüseyin Acan, <a href="https://arxiv.org/abs/1810.02040">Counting unlabeled interval graphs</a>, arXiv:1810.02040 [math.CO], 2018.
%H Hüseyin Acan, Sankardeep Chakraborty, Seungbum Jo, Srinivasa Rao Satti, <a href="https://arxiv.org/abs/1902.09228">Succinct Data Structures for Families of Interval Graphs</a>, arXiv:1902.09228 [cs.DS], 2019.
%H Phil Hanlon, <a href="http://dx.doi.org/10.1090/S0002-9947-1982-0662044-8">Counting interval graphs</a>, Trans. Amer. Math. Soc. 272 (1982), no. 2, 383-426.
%H S. Hougardy, <a href="http://dx.doi.org/10.1016/j.disc.2006.05.021">Classes of perfect graphs</a>, Discr. Math. 306 (2006), 2529-2571.
%H Yang, Joyce C.; Pippenger, Nicholas <a href="https://doi.org/10.1090/bproc/27">On the enumeration of interval graphs</a> Proc. Am. Math. Soc., Ser. B 4, 1-3 (2017).
%K nonn
%O 1,2
%A _N. J. A. Sloane_
%E a(21) onwards added by _N. J. A. Sloane_, Oct 19 2006 from the Robinson reference