OFFSET
1,1
COMMENTS
The embedding must map edges in the graph onto either horizontal or vertical grid lines of length 1 or diagonals of length sqrt(2). Vertices in the graph must map onto lattice points, and of course must preserve the incidence structure of the graph. A square in the lattice may have both diagonals present - their intersection does not count as an incidence.
Configurations differing only a rotation or reflection are not counted as different.
The resulting figures are variously called 'polysticks', 'polyedges' or 'polyforms'.
LINKS
N. J. A. Sloane, Illustration for a(1)=2, a(2)=6, a(3)=41. [Thanks to Peter Munn for correcting errors in my first drawing.]
CROSSREFS
KEYWORD
nonn,hard,more,nice
AUTHOR
James W. Anderson, Jul 15 2020
EXTENSIONS
a(7)-a(8) from John Mason, Aug 17 2021
STATUS
approved