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Number of n X 4 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
1

%I #6 Sep 04 2022 08:10:16

%S 6,63,997,15104,214635,2886700,37224679,464804972,5658641517,

%T 67497024458,791686330307,9155901061480,104627294693465,

%U 1183339450854998,13264070830389055,147510583604457748,1629077899911720149

%N Number of n X 4 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

%C Column 4 of A280480.

%H R. H. Hardin, <a href="/A280476/b280476.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 51*a(n-1) -1155*a(n-2) +15629*a(n-3) -144180*a(n-4) +980916*a(n-5) -5175036*a(n-6) +21885648*a(n-7) -75880896*a(n-8) +219014768*a(n-9) -531595200*a(n-10) +1091740992*a(n-11) -1902278464*a(n-12) +2810785536*a(n-13) -3508065024*a(n-14) +3668507648*a(n-15) -3171179520*a(n-16) +2217664512*a(n-17) -1211863040*a(n-18) +487784448*a(n-19) -128974848*a(n-20) +16777216*a(n-21) for n>22.

%e Some solutions for n=4

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

%e ..0..0..1..0. .0..0..0..2. .0..0..1..1. .1..1..1..0. .0..0..2..2

%e ..2..2..0..1. .1..1..2..2. .2..0..0..2. .1..2..0..0. .0..2..2..0

%e ..2..0..1..1. .1..2..2..2. .0..0..0..0. .2..2..2..2. .0..0..0..0

%Y Cf. A280480.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 04 2017