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A234557 Number of (n+1) X (1+1) 0..4 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
70, 220, 618, 1954, 5506, 17518, 49506, 158518, 449170, 1447510, 4111458, 13334374, 37954546, 123863638, 353202306, 1159606918, 3311711890, 10935135670, 31268536098, 103805608294, 297121857586, 991365572758, 2839736979906 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) + 18*a(n-2) - 54*a(n-3) - 80*a(n-4) + 240*a(n-5).
Empirical g.f.: 2*x*(35 + 5*x - 651*x^2 - 40*x^3 + 3000*x^4) / ((1 - 3*x)*(1 - 8*x^2)*(1 - 10*x^2)). - Colin Barker, Oct 15 2018
EXAMPLE
Some solutions for n=5:
3 4 2 3 1 3 0 0 2 1 2 2 4 4 3 3 3 3 4 3
3 0 4 1 3 1 0 4 0 3 0 4 0 4 4 0 0 4 0 3
1 2 2 3 1 3 2 2 1 0 3 3 2 2 0 0 4 4 4 3
4 1 3 0 3 1 4 0 0 3 4 0 0 4 4 0 0 4 0 3
1 2 1 2 1 3 1 1 4 3 3 3 3 3 4 4 2 2 3 2
4 1 4 1 2 0 4 0 0 3 0 4 0 4 4 0 4 0 0 3
CROSSREFS
Column 1 of A234564.
Sequence in context: A235310 A235303 A234564 * A245857 A227879 A072596
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 28 2013
STATUS
approved

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Last modified June 21 14:41 EDT 2024. Contains 373547 sequences. (Running on oeis4.)