A280436 - OEIS

%I #6 Jan 04 2017 13:14:01

%S 2,20,42,80,138,232,386,640,1062,1764,2934,4884,8134,13548,22562,

%T 37560,62498,103936,172746,286936,476318,790220,1310222,2171180,

%U 3595918,5952452,9848346,16286240,26920122,44477464,73454354,121259824,200099094

%N Number of nX4 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.

%C Column 4 of A280440.

%H R. H. Hardin, <a href="/A280436/b280436.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) -4*a(n-2) -2*a(n-3) +4*a(n-4) -a(n-6) for n>7.

%F Empirical g.f.: 2*x + 2*x^2*(10-19*x-4*x^2+13*x^3+x^5+2*x^4) / ( (x-1)^2*(x^2+x-1)^2 ). - _R. J. Mathar_, Jan 04 2017

%e Some solutions for n=4

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

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

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

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

%Y Cf. A280440.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 03 2017