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 A239851 Number of n X 1 0..3 arrays with no element equal to zero plus the sum of elements to its left or zero plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4. 10

%I #8 Feb 18 2018 08:33:29

%S 2,2,4,6,8,14,20,30,48,70,108,166,248,382,580,878,1344,2038,3100,4726,

%T 7176,10926,16628,25278,38480,58534,89036,135494,206104,313566,477092,

%U 725774,1104224,1679958,2555772,3888406,5915688,8999950,13692500

%N Number of n X 1 0..3 arrays with no element equal to zero plus the sum of elements to its left or zero plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4.

%C Column 1 of A239858.

%H R. H. Hardin, <a href="/A239851/b239851.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-2) +2*a(n-3).

%F Empirical g.f.: 2*x*(1 + x + x^2) / (1 - x^2 - 2*x^3). - _Colin Barker_, Feb 18 2018

%e All solutions for n=4:

%e ..3....3....2....2....2....3

%e ..2....2....3....3....3....2

%e ..3....3....3....2....3....2

%e ..2....3....3....2....2....2

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 28 2014

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Last modified April 14 07:18 EDT 2024. Contains 371655 sequences. (Running on oeis4.)