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 A251517 Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock summing to 2 3 4 5 6 7 8 9 or 10. 1

%I

%S 246,3798,58618,904734,13963994,215525422,3326498602,51342402526,

%T 792437518266,12230772022158,188774232427978,2913610912231614,

%U 44969742102454874,694079534186116462,10712678731366753642

%N Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock summing to 2 3 4 5 6 7 8 9 or 10.

%H R. H. Hardin, <a href="/A251517/b251517.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 15*a(n-1) + 8*a(n-2) - 20*a(n-3).

%F Empirical g.f.: 2*x*(123 + 54*x - 160*x^2) / (1 - 15*x - 8*x^2 + 20*x^3). - _Colin Barker_, Nov 30 2018

%e Some solutions for n=3:

%e ..1..3....3..1....2..2....3..1....1..1....0..3....0..1....0..3....2..1....3..1

%e ..2..0....3..2....2..2....1..1....2..0....2..3....0..3....3..2....2..0....2..2

%e ..3..1....3..0....0..2....1..3....0..0....1..2....2..2....0..1....1..3....2..0

%e ..1..3....0..3....0..2....3..2....2..0....1..1....3..2....2..1....3..3....3..2

%Y Column 1 of A251524.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 03 2014

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Last modified December 6 18:16 EST 2021. Contains 349567 sequences. (Running on oeis4.)