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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A269091 Number of n X 2 0..3 arrays with some element plus some horizontally or vertically adjacent neighbor totalling three exactly once. 2

%I #7 Mar 21 2018 11:53:10

%S 4,96,1152,11424,103488,889056,7375872,59698464,474360768,3715826016,

%T 28777886592,220814937504,1681292682048,12718165610976,95670977133312,

%U 716203564928544,5338972029467328,39651633731043936,293513242790716032

%N Number of n X 2 0..3 arrays with some element plus some horizontally or vertically adjacent neighbor totalling three exactly once.

%C Column 2 of A269097.

%H R. H. Hardin, <a href="/A269091/b269091.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 14*a(n-1) -49*a(n-2) for n>3.

%F Conjectures from _Colin Barker_, Mar 21 2018: (Start)

%F G.f.: 4*x*(1 + 10*x + x^2) / (1 - 7*x)^2.

%F a(n) = 96*7^(n-3)*(5*n-3) for n>1.

%F (End)

%e Some solutions for n=4:

%e ..2..0. .2..2. .3..3. .3..3. .1..3. .3..3. .2..2. .3..2. .3..3. .1..3

%e ..1..1. .2..2. .2..3. .2..2. .3..1. .0..1. .3..2. .2..3. .3..3. .0..1

%e ..1..1. .1..0. .3..1. .1..3. .2..2. .1..0. .1..0. .0..1. .1..0. .0..2

%e ..3..3. .3..2. .2..2. .3..3. .3..3. .0..1. .1..2. .0..2. .3..2. .2..2

%Y Cf. A269097.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 19 2016

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 10 16:14 EDT 2024. Contains 375790 sequences. (Running on oeis4.)