A280439 - OEIS

%I #7 Feb 13 2019 11:19:58

%S 20,120,236,386,574,834,1211,1784,2684,4128,6478,10334,16693,27208,

%T 44620,73470,121278,200490,331695,548936,908476,1503260,2486766,

%U 4112326,6797929,11232984,18554156,30634874,50561854,83419218,137578403

%N Number of n X 7 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.

%H R. H. Hardin, <a href="/A280439/b280439.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.: x*(20 + 40*x - 164*x^2 - 38*x^3 + 134*x^4 + 74*x^5 + 19*x^6) / ((1 - x)^2*(1 - x - x^2)^2). - _Colin Barker_, Feb 13 2019

%e Some solutions for n=4:

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

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

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

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

%Y Column 7 of A280440.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 03 2017