cp's OEIS Frontend

A239812 Number of n X 1 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of elements above it, modulo 4.

%I A239812 #7 Feb 21 2018 09:42:15
%S A239812 2,5,11,25,57,129,293,665,1509,3425,7773,17641,40037,90865,206221,
%T A239812 468025,1062197,2410689,5471133,12416905,28180549,63956625,145151533,
%U A239812 329425881,747642197,1696797025,3850933181,8739811625,19835272037,45016761649
%N A239812 Number of n X 1 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of elements above it, modulo 4.
%C A239812 Column 1 of A239819.
%H A239812 R. H. Hardin, <a href="/A239812/b239812.txt">Table of n, a(n) for n = 1..210</a>
%F A239812 Empirical: a(n) = a(n-1) + 2*a(n-2) + 2*a(n-3).
%F A239812 Empirical g.f.: x*(2 + 3*x + 2*x^2) / (1 - x - 2*x^2 - 2*x^3). - _Colin Barker_, Feb 21 2018
%e A239812 Some solutions for n=5:
%e A239812 ..2....2....2....2....3....2....2....3....2....3....2....2....3....3....2....3
%e A239812 ..1....1....2....2....1....1....1....3....2....1....1....1....2....3....2....2
%e A239812 ..3....2....3....2....2....3....2....2....2....3....2....3....1....1....2....3
%e A239812 ..1....1....2....1....1....1....3....3....1....3....1....1....1....3....2....2
%e A239812 ..1....2....1....2....1....3....3....3....3....1....1....2....2....1....3....2
%Y A239812 Cf. A239819.
%K A239812 nonn
%O A239812 1,1
%A A239812 _R. H. Hardin_, Mar 27 2014