login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A246474 Number of length n+3 0..3 arrays with no pair in any consecutive four terms totalling exactly 3. 1
60, 132, 292, 644, 1420, 3132, 6908, 15236, 33604, 74116, 163468, 360540, 795196, 1753860, 3868260, 8531716, 18817292, 41502844, 91537404, 201892100, 445287044, 982111492, 2166115084, 4777517212, 10537145916, 23240406916, 51258331044 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

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

Empirical g.f.: 4*x*(15 + 3*x + 7*x^2) / (1 - 2*x - x^3). - Colin Barker, Nov 06 2018

EXAMPLE

Some solutions for n=6:

..2....3....2....1....0....2....1....0....0....2....1....3....2....0....2....1

..0....3....2....1....2....2....3....0....2....0....1....3....3....0....2....3

..0....2....2....0....0....2....1....0....2....2....1....3....2....0....3....1

..2....2....2....1....0....2....1....0....2....2....0....3....3....1....3....3

..0....2....3....1....0....2....1....0....2....2....0....1....2....1....2....3

..0....2....3....0....0....2....1....0....3....0....0....1....2....1....3....3

..0....2....3....0....0....3....1....2....3....0....1....1....2....3....3....3

..0....0....3....1....0....2....3....0....3....0....0....3....2....1....2....1

..1....0....2....0....0....3....1....2....2....0....1....1....0....3....2....3

CROSSREFS

Column 3 of A246479.

Sequence in context: A044247 A044628 A181190 * A334407 A336628 A336443

Adjacent sequences:  A246471 A246472 A246473 * A246475 A246476 A246477

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 27 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 January 21 14:32 EST 2022. Contains 350479 sequences. (Running on oeis4.)