A255540 - OEIS

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, 2, 6, 15, 51, 173, 681, 2682 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,3`
	COMMENTS	`Also the number of polyplets (A030222) on n points up to isomorphism of adjacency graphs.`
	LINKS	`Table of n, a(n) for n=1..9.` `P. C. Staecker, Some enumerations of binary digital images, arXiv 1502.06236 [math.CO], 2015 (see table p. 6).` `P. C. Staecker, Digital image enumerations`
	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: A237262 A291848 A196961 * A323926 A256982 A047870` `Adjacent sequences: A255537 A255538 A255539 * A255541 A255542 A255543`
	KEYWORD	`nonn,hard,more`
	AUTHOR	`P. Christopher Staecker, Feb 24 2015`
	STATUS	`approved`

Last modified August 10 16:24 EDT 2022. Contains 356039 sequences. (Running on oeis4.)