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A255539 Number of digital images in Z^2 with 4-adjacency on n points up to isomorphism. 1
1, 1, 1, 3, 4, 10, 19, 51, 112, 300, 746, 2042 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Also the number of polyominoes on n points, up to isomorphism of the adjacency graph.

Also the number of "grid graphs" (finite induced subgraphs of the integer lattice using only horizontal and vertical edges) on n vertices.

LINKS

Table of n, a(n) for n=1..12.

P. C. Staecker, Some enumerations of binary digital images, arXiv 1502.06236 [math.CO], 2015.

CROSSREFS

Sequence in context: A139797 A306334 A036649 * A321197 A109887 A200981

Adjacent sequences:  A255536 A255537 A255538 * A255540 A255541 A255542

KEYWORD

nonn,more,hard

AUTHOR

P. Christopher Staecker, Feb 24 2015

STATUS

approved

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Last modified March 23 18:13 EDT 2019. Contains 321433 sequences. (Running on oeis4.)