%I #7 Dec 12 2014 11:30:05
%S 1,1,1,2,3,5,18
%N Number of nonisomorphic arrangements of n lines in the real projective plane, including the arrangement where all the lines pass through a common point.
%C See the illustration of initial terms in A048872.
%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. 4.
%Y Equals A048872 + 1. Cf. A003036, A048873. Different from A121510.
%K nonn,nice,more
%O 0,4
%A _N. J. A. Sloane_, Nov 09 2007