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!)
A165380 Number of slanted n X n (i=1..n)X(j=i..n+i-1) 1..4 arrays with all 1s connected, all 2s connected, all 3s connected, all 4s connected, 1 in the upper left corner, 2 in the upper right corner, 3 in the lower left corner, 4 in the lower right corner, and with no element having more than 3 neighbors with the same value 0
1, 40, 1012, 18900, 598332, 30346872, 3445935988 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

Table of n, a(n) for n=2..8.

EXAMPLE

Some solutions for n=4

...1.1.1.2.........1.2.2.2.........1.1.1.2.........1.1.4.2......

.....2.2.2.4.........2.2.2.2.........1.1.2.2.........4.4.2.4....

.......2.3.4.4.........3.3.2.4.........1.1.2.4.........4.4.4.4..

.........3.4.4.4.........3.3.4.4.........3.2.4.4.........3.3.4.4

------

...1.2.2.2.........1.2.2.2.........1.1.2.2.........1.1.1.2......

.....3.3.2.2.........3.3.2.4.........2.2.2.2.........2.2.2.2....

.......3.3.2.2.........3.3.4.4.........3.3.2.2.........3.3.3.4..

.........3.2.2.4.........3.3.4.4.........3.3.4.4.........3.3.4.4

------

...1.1.1.2.........1.1.2.2.........1.1.1.2.........1.1.2.2......

.....1.1.2.2.........1.1.3.3.........2.2.2.2.........1.2.2.2....

.......3.3.3.4.........1.3.3.4.........3.3.2.3.........3.3.2.4..

.........3.4.4.4.........3.3.4.4.........3.3.3.4.........3.3.4.4

CROSSREFS

Sequence in context: A004349 A016092 A028228 * A075907 A062143 A284838

Adjacent sequences:  A165377 A165378 A165379 * A165381 A165382 A165383

KEYWORD

nonn

AUTHOR

R. H. Hardin Sep 17 2009

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 April 7 04:20 EDT 2020. Contains 333292 sequences. (Running on oeis4.)