|
%I #7 Feb 13 2019 11:33:29
%S 0,9,50,144,325,670,1316,2502,4654,8521,15412,27612,49085,86695,
%T 152282,266222,463487,803970,1390026,2396244,4119894,7066303,12093158,
%U 20654128,35209707,59919341,101806274,172716156,292607401,495074182,836609600
%N Number of n X 3 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
%H R. H. Hardin, <a href="/A280549/b280549.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 5*a(n-1) - 7*a(n-2) - 2*a(n-3) + 10*a(n-4) - 2*a(n-5) - 5*a(n-6) + a(n-7) + a(n-8) for n>10.
%F Empirical g.f.: x^2*(9 + 5*x - 43*x^2 - 27*x^3 + 63*x^4 + 47*x^5 - 33*x^6 - 25*x^7 + 8*x^8) / ((1 - x)^2*(1 - x - x^2)^3). - _Colin Barker_, Feb 13 2019
%e Some solutions for n=4:
%e ..0..1..1. .0..1..1. .0..1..1. .0..1..0. .0..1..1. .0..1..0. .0..1..1
%e ..1..0..0. .1..0..0. .1..0..0. .1..0..0. .1..0..1. .1..0..0. .0..0..1
%e ..1..1..0. .0..1..0. .0..1..1. .0..1..0. .1..1..0. .0..1..1. .1..1..0
%e ..1..0..1. .0..1..0. .1..1..0. .0..0..1. .1..0..1. .1..0..1. .0..0..1
%Y Column 3 of A280554.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 05 2017
|
