A359519 - OEIS

A359519

Number of free polyominoes of n cells with multiply-connected interiors.

0, 0, 0, 0, 0, 0, 0, 1, 2, 16, 70, 378, 1772, 8456, 38623, 174400, 771944, 3378937 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,9`
	LINKS	`Table of n, a(n) for n=1..18.`
	FORMULA	`a(n) = A000105(n) - A342537(n) (all free polyominoes minus simply-connected interior polyominoes).`
	EXAMPLE	`a(8) = 1 because of:` `OOO` `O O` `OOO`
	CROSSREFS	`Cf. A000104, A000105, A001419, A342537, A359520.` `Sequence in context: A034579 A006733 A034580 * A209538 A006729 A007758` `Adjacent sequences: A359516 A359517 A359518 * A359520 A359521 A359522`
	KEYWORD	`nonn,more`
	AUTHOR	`John Mason, Jan 04 2023`
	STATUS	`approved`

Last modified March 22 18:49 EDT 2023. Contains 361433 sequences. (Running on oeis4.)