login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A319321 a(n) is the number of d+/d- diagonally convex polyplets (polyominoes which need only touch at corners) with n cells. 0
1, 4, 20, 108, 600, 3368, 18968, 106906, 602532, 3395402, 19131460, 107788900, 607274848 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A polyplet is d+ [d-] diagonally convex if the intersection of its interior with any line of slope 1 [-1] through the centers of the cells is connected.

LINKS

Table of n, a(n) for n=1..13.

Adam Gruber, Java program to count lattice animals.

EXAMPLE

The only tetraplets that are not d+ diagonally convex are two animals consisting of a horizontal domino and a vertical domino joined at a corner. So a(4) = A006770(4) - 2 = 108.

CROSSREFS

Cf. A006770 (fixed polyplets), A187077 (row convex polyplets), A187276 (d+/d- diagonally convex polyominoes).

Sequence in context: A263965 A265084 A321111 * A321574 A225621 A020084

Adjacent sequences:  A319318 A319319 A319320 * A319322 A319323 A319324

KEYWORD

nonn,more

AUTHOR

David Bevan, Sep 27 2018

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 28 04:00 EDT 2022. Contains 354903 sequences. (Running on oeis4.)