The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A216583 Number of unit-conjoined polydominoes of order n. 9
 1, 1, 3, 20, 171, 1733, 18962, 215522, 2507188, 29635101 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS A unit-conjoined polydomino is formed from n 1 X 2 non-overlapping rectangles (or dominoes) such that each pair of touching rectangles shares an edge of length 1. The internal arrangement of dominoes is not significant: figures are counted as distinct only if the shapes of their perimeters are different. Figures that differ only by a rotation and/or reflection are regarded as equivalent (cf. A216595). This sequence is A216492 without the condition that the adjacency graph of the dominoes forms a tree. This is a subset of polydominoes. It appears that A216492(n) < a(n) < A056785(n) < A056786(n) < A210996(n) < A210988(n) < A210986(n), if n >= 3. - Omar E. Pol, Sep 17 2012 LINKS Table of n, a(n) for n=0..9. César E. Lozada, Illustration of terms n <= 4 of A216583 N. J. A. Sloane, Illustration of initial terms of A056786, A216598, A216583, A216595, A216492, A216581 (Exclude figures marked (A)) N. J. A. Sloane, Illustration of third term of A056786, A216598, A216583, A216595, A216492, A216581 (a better drawing for the third term) M. Vicher, Polyforms Index entries for sequences related to dominoes CROSSREFS Cf. A056786, A216598, A216583, A216595, A216492, A216581. Sequence in context: A051643 A213377 A357094 * A354018 A154644 A321276 Adjacent sequences: A216580 A216581 A216582 * A216584 A216585 A216586 KEYWORD nonn,more,hard AUTHOR N. J. A. Sloane, Sep 09 2012 EXTENSIONS a(4)-a(6) added by César Eliud Lozada, Sep 09 2012 a(7)-a(9) and name edited by Aaron N. Siegel, May 18 2022 STATUS approved

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

Last modified May 21 05:34 EDT 2024. Contains 372728 sequences. (Running on oeis4.)