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A235284
Number of (n+1) X (3+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
68, 104, 148, 248, 380, 680, 1108, 2072, 3548, 6824, 12148, 23768, 43580, 86120, 161428, 320792, 611228, 1218344, 2349748, 4691288, 9129980, 18243560, 35745748, 71458712, 140726108, 281386664, 556264948, 1112398808, 2205403580, 4410545000
OFFSET
1,1
COMMENTS
Column 3 of A235289.
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)
EXAMPLE
Some solutions for n=4:
3 1 3 0 0 2 0 2 1 3 2 3 1 0 1 0 3 2 3 2
1 3 1 2 2 0 2 0 2 0 3 0 0 3 0 3 0 3 0 3
3 1 3 0 0 2 0 2 0 2 1 2 3 2 3 2 2 1 2 1
1 3 1 2 2 0 2 0 2 0 3 0 0 3 0 3 0 3 0 3
3 1 3 0 0 2 0 2 0 2 1 2 3 2 3 2 2 1 2 1
CROSSREFS
Sequence in context: A352040 A217776 A039540 * A373209 A250765 A048889
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 05 2014
STATUS
approved