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A235283
Number of (n+1) X (2+1) 0..3 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 4 (constant-stress 1 X 1 tilings).
1
40, 68, 104, 188, 304, 572, 968, 1868, 3280, 6428, 11624, 22988, 42544, 84572, 159368, 317708, 607120, 1212188, 2341544, 4678988, 9113584, 18218972, 35712968, 71409548, 140660560, 281288348, 556133864, 1112202188, 2205141424, 4410151772
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) + 3*a(n-2) - 15*a(n-3) + 4*a(n-4) + 18*a(n-5) - 12*a(n-6).
Empirical g.f.: 4*x*(10 - 13*x - 55*x^2 + 68*x^3 + 72*x^4 - 84*x^5) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)*(1 - 3*x^2)). - Colin Barker, Oct 18 2018
EXAMPLE
Some solutions for n=4:
0 1 0 3 2 3 0 1 0 1 3 2 0 1 0 0 2 0 0 3 0
3 0 3 0 3 0 3 0 3 2 0 3 3 0 3 3 1 3 2 1 2
2 3 2 3 2 3 1 2 1 0 2 1 0 1 0 0 2 0 0 3 0
3 0 3 0 3 0 3 0 3 2 0 3 3 0 3 3 1 3 1 0 1
2 3 2 2 1 2 0 1 0 0 2 1 1 2 1 0 2 0 0 3 0
CROSSREFS
Column 2 of A235289.
Sequence in context: A232870 A338373 A355778 * A134216 A043156 A039333
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 05 2014
STATUS
approved