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!)
A220688 T(n,k)=Number of ways to reciprocally link elements of an nXk array either to themselves or to exactly two horizontal, vertical or antidiagonal neighbors 7
1, 1, 1, 1, 4, 1, 1, 12, 12, 1, 1, 37, 94, 37, 1, 1, 114, 745, 745, 114, 1, 1, 351, 5851, 15452, 5851, 351, 1, 1, 1081, 46027, 312603, 312603, 46027, 1081, 1, 1, 3329, 362057, 6349886, 15978924, 6349886, 362057, 3329, 1, 1, 10252, 2847943, 128995678 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Table starts

.1.....1.........1.............1................1....................1

.1.....4........12............37..............114..................351

.1....12........94...........745.............5851................46027

.1....37.......745.........15452...........312603..............6349886

.1...114......5851........312603.........15978924............822649205

.1...351.....46027.......6349886........822649205.........107713940118

.1..1081....362057.....128995678......42362190063.......14108684022136

.1..3329...2847943....2620320833....2181341369109.....1848014307847883

.1.10252..22401961...53226950200..112319870453715...242044667782801540

.1.31572.176214299.1081210102382.5783510938076077.31702119421997470360

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..180

EXAMPLE

Some solutions for n=3 k=4 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)

.00.78.00.00...68.46.47.00...00.78.78.00...68.46.46.47...68.46.47.00

.38.26.46.48...28.37.67.48...38.23.27.78...28.67.34.78...28.38.00.78

.26.46.46.24...23.36.46.24...26.34.36.24...23.00.36.24...26.24.36.24

CROSSREFS

Column 2 is A099098

Sequence in context: A099759 A072590 A111636 * A146990 A051433 A163366

Adjacent sequences:  A220685 A220686 A220687 * A220689 A220690 A220691

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin Dec 17 2012

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 20 17:16 EDT 2020. Contains 337265 sequences. (Running on oeis4.)