%I #9 May 21 2023 12:56:39
%S 1,1,1,2,4,9,20,51,128,338,882,2350,6238,16693,44561,119339,319104,
%T 854420,2285357
%N Number of free linear polycubes of size n, identifying rotations and reflections and avoiding neighbors at [0,0,+-2], [0,+-2,0], and [+-2,0,0].
%C Linear polycubes have two end points with one neighbor, the remaining cubes all have two neighbors.
%C When a cube [x,y,z] is in the polycube then neither of the six cubes [x+-2,y,z], [x,y+-2,z], [x,y,z+-2] can be in the polycube. For example, no three cubes can be in a row.
%Y Cf. A363204 (linear and avoiding at [+-1,+-1,+-1]).
%K nonn,more
%O 1,4
%A _Joerg Arndt_ and _Márk Péter Légrádi_, May 21 2023