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A231398 Number of (2+1)X(n+1) 0..2 arrays with no element unequal to a strict majority of its horizontal, diagonal and antidiagonal neighbors, with values 0..2 introduced in row major order.

%I A231398 #6 Jul 23 2025 06:27:39
%S A231398 4,8,38,90,363,1163,3985,14650,50088,185178,665415,2425915,8953631,
%T A231398 32773916,121530364,449147910,1665804417,6189859849,22993326811,
%U A231398 85585457988,318520365520,1186296435208,4419902305187,16469639460901
%N A231398 Number of (2+1)X(n+1) 0..2 arrays with no element unequal to a strict majority of its horizontal, diagonal and antidiagonal neighbors, with values 0..2 introduced in row major order.
%C A231398 Row 2 of A231396
%H A231398 R. H. Hardin, <a href="/A231398/b231398.txt">Table of n, a(n) for n = 1..210</a>
%F A231398 Empirical: a(n) = 4*a(n-1) +12*a(n-2) -43*a(n-3) -103*a(n-4) +278*a(n-5) +418*a(n-6) -1103*a(n-7) -883*a(n-8) +2549*a(n-9) +1514*a(n-10) -4171*a(n-11) -1969*a(n-12) +4818*a(n-13) +1876*a(n-14) -3992*a(n-15) -1124*a(n-16) +2288*a(n-17) +288*a(n-18) -752*a(n-19) +96*a(n-21)
%e A231398 Some solutions for n=6
%e A231398 ..0..0..1..0..0..1..1....0..1..1..1..1..1..2....0..1..0..0..0..0..1
%e A231398 ..0..1..0..1..1..0..0....0..0..1..1..1..2..2....1..0..1..1..0..1..0
%e A231398 ..1..0..1..1..0..0..0....0..0..1..1..1..2..2....0..1..1..1..1..0..1
%K A231398 nonn
%O A231398 1,1
%A A231398 _R. H. Hardin_, Nov 08 2013