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!)
A271802 Number of cuttings of an n X n checkerboard along grid lines into two pieces with holes disallowed. 1
0, 6, 52, 614, 16000, 1114394, 220762028, 127074234622, 215163221802400, 1080509693050320314, 16181730102294154610684, 725449589191165593072311582, 97631783799192329642727718567824, 39528641527526180063041016094650084850 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Equivalently, the number of partitionings of an n X n checkerboard into two edgewise-connected simply-connected sets. (Cf. A068416).

Each part is required to contain at least one cell and cuttings are considered different if they only differ by rotation or reflection.

LINKS

Table of n, a(n) for n=1..14.

FORMULA

a(n) = A068416(n) - A140517(n-2).

MATHEMATICA

A068416 = Cases[Import["https://oeis.org/A068416/b068416.txt", "Table"], {_, _}][[All, 2]];

A140517 = Cases[Import["https://oeis.org/A140517/b140517.txt", "Table"], {_, _}][[All, 2]];

a[n_] := If[n == 1, 0, A068416[[n]] - A140517[[n - 1]]];

Array[a, 14] (* Jean-Fran├žois Alcover, Sep 15 2019 *)

CROSSREFS

Sequence in context: A144345 A294158 A209306 * A097820 A166889 A164894

Adjacent sequences:  A271799 A271800 A271801 * A271803 A271804 A271805

KEYWORD

nonn

AUTHOR

Andrew Howroyd, Apr 14 2016

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 September 27 07:28 EDT 2021. Contains 347673 sequences. (Running on oeis4.)