The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A286345 Number of (n,3)-polyominoes. 2
 0, 3, 17, 151, 955 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS (n,k)-polyominoes are disconnected polyominoes with n visible squares and k transparent squares. Importantly, k must be the least number of transparent squares that need to be converted to visible squares to make all the visible squares connected. Note that a regular polyomino of order n is a (n,0)-polyomino, since all its visible squares are already connected. For more details see the paper by Kamenetsky and Cooke. LINKS Dmitry Kamenetsky and Tristrom Cooke, Tiling rectangles with holey polyominoes, arXiv:1411.2699 [cs.CG], 2015. EXAMPLE We can represent these polyominoes as binary matrices, where 1 means visible square and 0 means transparent square. Note that we need to flip (change to 1) three 0's to make all the 1's connected. This also means that the Manhattan distance between any pair of 1's is at most 4. Here are all such polyominoes for n=2: 10001 1000 100       0001 000            001 CROSSREFS Cf. A286194, A286344. Sequence in context: A213507 A305471 A135750 * A303063 A209305 A182957 Adjacent sequences:  A286342 A286343 A286344 * A286346 A286347 A286348 KEYWORD nonn,more AUTHOR Dmitry Kamenetsky, May 07 2017 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 5 08:21 EDT 2020. Contains 334829 sequences. (Running on oeis4.)