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!)
A269103 Number of n X 2 0..3 arrays with some element plus some horizontally or vertically adjacent neighbor totalling three no more than once. 2

%I #9 Mar 21 2018 12:17:26

%S 16,180,1740,15540,132300,1090740,8787660,69580980,543538380,

%T 4200069300,32167589580,244542858420,1847388128460,13880833735860,

%U 103809654007500,773174303047860,5737767196302540,42443199898890420,313054205965641420

%N Number of n X 2 0..3 arrays with some element plus some horizontally or vertically adjacent neighbor totalling three no more than once.

%C Column 2 of A269109.

%H R. H. Hardin, <a href="/A269103/b269103.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*(4 - 11*x + x^2) / (1 - 7*x)^2.

%F a(n) = 60*7^(n-3)*(8*n+5) for n>1.

%F (End)

%e Some solutions for n=4:

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

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

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

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

%Y Cf. A269109.

%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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)