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!)
A238768 Number of n X 1 0..3 arrays with no element equal to the sum modulo 4 of elements to its left or elements above it. 3
3, 6, 14, 32, 72, 164, 372, 844, 1916, 4348, 9868, 22396, 50828, 115356, 261804, 594172, 1348492, 3060444, 6945772, 15763644, 35776076, 81194908, 184274348, 418216316, 949154828, 2154136156, 4888878444, 11095460412, 25181489612 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A238775.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

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

Empirical g.f.: x*(3 + 3*x + 2*x^2) / (1 - x - 2*x^2 - 2*x^3). - Colin Barker, Feb 24 2018

EXAMPLE

Some solutions for n=5:

..3....3....2....1....1....2....1....3....2....1....3....3....1....1....2....1

..1....1....3....2....2....3....3....2....3....3....1....2....2....2....1....3

..2....2....3....1....2....3....1....2....2....3....2....3....2....2....2....2

..1....3....1....3....3....3....2....2....2....2....1....1....3....2....2....1

..1....3....3....2....1....1....2....2....2....2....2....2....3....1....2....2

CROSSREFS

Cf. A238775.

Sequence in context: A209357 A090165 A129954 * A272362 A182905 A330053

Adjacent sequences:  A238765 A238766 A238767 * A238769 A238770 A238771

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 05 2014

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 August 13 22:46 EDT 2020. Contains 336473 sequences. (Running on oeis4.)