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T(n,k)=Number of nXk 0..1 arrays with each 1 horizontally, vertically or antidiagonally adjacent to 1, 2 or 4 neighboring 1s.
7

%I #4 Dec 17 2017 15:12:48

%S 1,2,2,4,10,4,7,28,28,7,12,86,132,86,12,21,279,671,671,279,21,37,869,

%T 3444,5696,3444,869,37,65,2728,17558,49872,49872,17558,2728,65,114,

%U 8596,89613,430522,742601,430522,89613,8596,114,200,27004,457188,3713779

%N T(n,k)=Number of nXk 0..1 arrays with each 1 horizontally, vertically or antidiagonally adjacent to 1, 2 or 4 neighboring 1s.

%C Table starts

%C ...1.....2.......4.........7..........12............21..............37

%C ...2....10......28........86.........279...........869............2728

%C ...4....28.....132.......671........3444.........17558...........89613

%C ...7....86.....671......5696.......49872........430522.........3713779

%C ..12...279....3444.....49872......742601......10781621.......157255466

%C ..21...869...17558....430522....10781621.....263456105......6468185511

%C ..37..2728...89613...3713779...157255466....6468185511....267838310277

%C ..65..8596..457188..32095222..2296958734..158971670482..11100574753607

%C .114.27004.2333009.277299810.33523275696.3904685293187.459672982178410

%H R. H. Hardin, <a href="/A296643/b296643.txt">Table of n, a(n) for n = 1..241</a>

%F Empirical for column k:

%F k=1: a(n) = 2*a(n-1) -a(n-2) +a(n-3)

%F k=2: a(n) = 3*a(n-1) -a(n-2) +6*a(n-3) -6*a(n-4) +6*a(n-5) -5*a(n-6) +3*a(n-7) -a(n-8)

%F k=3: [order 22]

%F k=4: [order 74]

%e Some solutions for n=4 k=4

%e ..0..1..0..0. .1..1..0..0. .1..0..0..1. .0..1..1..1. .0..0..0..1

%e ..0..1..0..1. .1..0..1..1. .1..0..1..0. .1..0..0..0. .1..1..0..1

%e ..0..1..1..0. .0..0..0..1. .1..0..0..0. .1..0..0..1. .0..1..0..0

%e ..1..1..1..0. .1..1..1..0. .1..1..1..0. .1..0..1..0. .0..1..1..0

%Y Column 1 is A005251(n+2).

%Y Column 2 is A296380.

%K nonn,tabl

%O 1,2

%A _R. H. Hardin_, Dec 17 2017

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Last modified September 21 22:57 EDT 2024. Contains 376090 sequences. (Running on oeis4.)