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!)
A195956 Number of n X 2 0..4 arrays with each element equal to the number its horizontal and vertical neighbors unequal to itself. 1
1, 1, 6, 5, 5, 14, 21, 29, 54, 93, 149, 254, 437, 733, 1238, 2109, 3573, 6046, 10261, 17405, 29494, 50013, 84821, 143806, 243829, 413469, 701078, 1188733, 2015669, 3417822, 5795285, 9826621, 16662262, 28252829, 47906069, 81230590, 137736245 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Column 2 of A195962.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = a(n-1) +3*a(n-3) -a(n-4) -2*a(n-6).

Empirical g.f.: x*(1 + 5*x^2 - 4*x^3 - 2*x^4 - 8*x^5) / ((1 - x)*(1 + x + x^2)*(1 - x - 2*x^3)). - Colin Barker, May 08 2018

EXAMPLE

All solutions for n=5:

..2..1....1..2....2..1....0..0....1..2

..3..1....1..3....1..1....0..0....1..1

..1..1....1..1....1..3....0..0....3..1

..1..3....3..1....1..1....0..0....1..1

..1..2....2..1....2..1....0..0....1..2

CROSSREFS

Cf. A195962.

Sequence in context: A167918 A070860 A198354 * A336814 A019850 A185273

Adjacent sequences:  A195953 A195954 A195955 * A195957 A195958 A195959

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 25 2011

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 15 17:45 EDT 2021. Contains 348033 sequences. (Running on oeis4.)