A281931 - OEIS

%I #4 Feb 02 2017 08:19:36

%S 0,1,20,312,3573,31410,252630,1925590,14065552,99735307,691339079,

%T 4705890596,31562889402,209107683151,1370993621183,8908621893421,

%U 57438444240641,367809712917088,2341050421702590,14819986285211521

%N Number of nX3 0..1 arrays with no element equal to more than four of its king-move neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

%C Column 3 of A281936.

%H R. H. Hardin, <a href="/A281931/b281931.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 15*a(n-1) -63*a(n-2) +23*a(n-3) +3*a(n-4) +1161*a(n-5) +208*a(n-6) -2013*a(n-7) -8424*a(n-8) -6999*a(n-9) +7797*a(n-10) +25689*a(n-11) +44356*a(n-12) +27282*a(n-13) -498*a(n-14) -60721*a(n-15) -115722*a(n-16) -113223*a(n-17) -120471*a(n-18) -77700*a(n-19) -35280*a(n-20) -21952*a(n-21) for n>26

%e Some solutions for n=4

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

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

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

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

%Y Cf. A281936.

%K nonn

%O 1,3

%A _R. H. Hardin_, Feb 02 2017