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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A342963 a(n) is the number of sticky polyhexes of with 2*n cells. 0
1, 2, 15, 110, 1051, 10636, 113290, 1234189, 13674761, 153289285 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A sticky polyhex is defined as follows:

- A single dihex (polyhex of size 2) is a sticky polyhex.

- If a polyhex X is sticky, X plus a dihex Y is also sticky if X and Y share at least two unit sides.

- Any polyhex that cannot be formed by the above definition is not sticky.

This sequence counts free polyhexes; two polyhexes which are equivalent under reflection and/or rotation are counted only once.

a(n) < A000228(2n) for n > 1.

LINKS

Table of n, a(n) for n=1..10.

Woosuk Kwak, Sticky Polyhexes, Code Golf Stack Exchange.

EXAMPLE

The two sticky tetrahexes are:

    * *    * * *

     * *    *

The following is the full list of 15 sticky hexahexes (polyhexes of size 6):

    * * *    * * *    *        * * * *    * * *

     * *      * *    * * * *    * *          * * *

      *          *        *

---

    * *       *        * *       * *     * * *

     * * *   * * * *    * * *   * * *       * *

        *       *      *         *         *

---

    * * *    * * *    * * * *   * * *    * * *

       * *    * * *    *   *       *        * *

          *                       * *        *

CROSSREFS

Cf. A000228.

Sequence in context: A062808 A162773 A140637 * A022026 A026113 A052874

Adjacent sequences:  A342960 A342961 A342962 * A342964 A342965 A342966

KEYWORD

nonn,hard,more

AUTHOR

Woosuk Kwak, Mar 31 2021

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 21 15:18 EDT 2021. Contains 348155 sequences. (Running on oeis4.)