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A235271
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 5 (constant-stress 1 X 1 tilings).
1
40, 100, 208, 520, 1120, 2800, 6208, 15520, 35200, 88000, 203008, 507520, 1185280, 2963200, 6980608, 17451520, 41359360, 103398400, 246059008, 615147520, 1467965440, 3669913600, 8774238208, 21935595520, 52511211520, 131278028800
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 10*a(n-2) - 24*a(n-4).
Conjectures from Colin Barker, Oct 17 2018: (Start)
G.f.: 4*x*(2 + 5*x)*(5 - 24*x^2) / ((1 - 2*x)*(1 + 2*x)*(1 - 6*x^2)).
a(n) = (-2)^n + 9*2^n + 6^((1/2)*(-1+n))*(12-12*(-1)^n + 5*sqrt(6) + 5*(-1)^n*sqrt(6)).
(End)
EXAMPLE
Some solutions for n=4:
3 2 2 4 2 0 4 2 4 3 1 3 0 4 2 4 1 4 4 1
0 4 3 0 1 4 0 3 0 4 3 0 3 2 3 0 4 2 1 3
3 2 0 2 4 2 3 1 1 0 2 4 0 4 2 4 0 3 3 0
0 4 3 0 1 4 0 3 0 4 4 1 1 0 3 0 2 0 0 2
4 3 0 2 2 0 2 0 2 1 1 3 0 4 0 2 1 4 3 0
CROSSREFS
Column 1 of A235280.
Sequence in context: A185791 A092889 A235280 * A033832 A235017 A043219
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 05 2014
STATUS
approved