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%I M2369 #24 Oct 27 2023 08:08:36
%S 0,0,1,1,3,4,11,21,55,124,327,815,2177,5712,15465,41727,114291,313504,
%T 866963,2404251,6701321,18733340,52557441,147849031,417080105,
%U 1179355476,3342487033,9492629497,27011665839,77000574224
%N Number of unlabeled reduced unit interval graphs on n nodes.
%D R. W. Robinson, 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="/A005218/b005218.txt">Table of n, a(n) for n = 1..190</a>
%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.
%F G.f.: -z + (1/4)*(1+2z-z^2)/sqrt((1+z^2)*(1-3z^2)) - (1/4)*sqrt((1-3z)/(1+z)). - _Emeric Deutsch_, Nov 19 2004
%p G:=-z+(1+2*z-z^2)/4/sqrt((1+z^2)*(1-3*z^2))-sqrt((1-3*z)/(1+z))/4: Gser:=series(G,z=0,30): seq(coeff(Gser,z^n),n=1..28); # _Emeric Deutsch_, Nov 19 2004
%K nonn
%O 1,5
%A _N. J. A. Sloane_
%E More terms from _Emeric Deutsch_, Nov 19 2004
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