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A209522 Number of nX3 0..7 arrays with every 2X2 subblock containing exactly one value repeat, and new values 0..7 introduced in row major order.

%I A209522 #7 Jul 22 2025 21:47:44
%S A209522 5,57,2027,107693,7700397,687132348,71519658191,8190834795146,
%T A209522 990354435624550,123286203872982432,15583473550178836892,
%U A209522 1985385176761852694734,253978177065210815069458
%N A209522 Number of nX3 0..7 arrays with every 2X2 subblock containing exactly one value repeat, and new values 0..7 introduced in row major order.
%C A209522 Column 3 of A209527
%H A209522 R. H. Hardin, <a href="/A209522/b209522.txt">Table of n, a(n) for n = 1..210</a>
%F A209522 Empirical: a(n) = 272*a(n-1) -24648*a(n-2) +828436*a(n-3) +149527*a(n-4) -622108500*a(n-5) +12598172586*a(n-6) -33558174264*a(n-7) -1578553176492*a(n-8) +17819275800656*a(n-9) -28667330106760*a(n-10) -594252767603616*a(n-11) +3792849444610432*a(n-12) -4923895161267584*a(n-13) -25653638667831936*a(n-14) +97101168572132352*a(n-15) -88244422976636928*a(n-16) -79190406866239488*a(n-17) +174755710679777280*a(n-18) -81018004244004864*a(n-19) +7489524376535040*a(n-20) for n>21
%e A209522 Some solutions for n=5
%e A209522 ..0..0..0....0..0..1....0..0..0....0..0..0....0..0..1....0..1..0....0..0..0
%e A209522 ..1..2..1....1..2..2....1..2..1....1..2..1....2..1..3....0..2..1....1..2..1
%e A209522 ..0..0..1....0..0..1....3..2..3....0..0..0....3..1..0....0..1..0....0..0..0
%e A209522 ..1..2..0....1..2..0....0..0..0....1..2..1....0..0..2....0..2..1....1..2..1
%e A209522 ..0..0..1....2..0..1....1..2..1....3..2..3....1..2..1....1..1..0....3..1..0
%K A209522 nonn
%O A209522 1,1
%A A209522 _R. H. Hardin_ Mar 10 2012