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A255540
Number of connected digital images in Z^2 (regarding each point as connected to its 8 neighbors) on n points up to isomorphism.
1
1, 1, 2, 6, 15, 51, 173, 681, 2682
OFFSET
1,3
COMMENTS
Also the number of polyplets (A030222) on n points up to isomorphism of adjacency graphs.
LINKS
P. C. Staecker, Some enumerations of binary digital images, arXiv 1502.06236 [math.CO], 2015 (see table p. 6).
EXAMPLE
For n=4 the a(4)=6 images are:
X X X X XX X X
X X X X XX XX XX
X X X X X
X
CROSSREFS
Cf. A255539.
Sequence in context: A363207 A196961 A368411 * A323926 A256982 A372853
KEYWORD
nonn,hard,more
AUTHOR
STATUS
approved