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!)
A222834 Number of n X 4 0..3 arrays with no element equal to another at a city block distance of exactly two, and new values 0..3 introduced in row major order. 1
7, 96, 216, 600, 1536, 4056, 10584, 27744, 72600, 190104, 497664, 1302936, 3411096, 8930400, 23380056, 61209816, 160249344, 419538264, 1098365400, 2875557984, 7528308504, 19709367576, 51599794176, 135090015000, 353670250776 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A222838.

LINKS

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

FORMULA

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

Conjectures from Colin Barker, Aug 16 2018: (Start)

G.f.: x*(7 + 82*x + 10*x^2 - 17*x^3) / ((1 + x)*(1 - 3*x + x^2)).

a(n) = (3/5)*2^(2-n)*((-1)^n*2^(2+n) + (3-sqrt(5))^(1+n) + (3+sqrt(5))^(1+n)) for n>1.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A222838.

Sequence in context: A239999 A054932 A217240 * A327676 A338075 A177879

Adjacent sequences:  A222831 A222832 A222833 * A222835 A222836 A222837

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 06 2013

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 27 23:26 EDT 2020. Contains 338047 sequences. (Running on oeis4.)