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%I #9 Dec 12 2014 10:39:38
%S 1,1,1,4,11
%N Number of non-isomorphic arrangements of n lines in the real projective plane such that the lines do not pass through a common point and no point belongs to more than 2 lines.
%C These are called simple arrangements.
%D J. E. Goodman and J. O'Rourke, editors, Handbook of Discrete and Computational Geometry, CRC Press, 1997, p. 102.
%D B. Grünbaum, Arrangements and Spreads. American Mathematical Society, Providence, RI, 1972, p. 6.
%Y Cf. A003036, A048872.
%K nonn,nice,more
%O 3,4
%A _N. J. A. Sloane_
%E The next term is conjectured to be 135.