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A183813 1/81 the number of (n+1) X 3 0..2 arrays with no 2 X 2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor. 1
8, 162, 3256, 65640, 1321860, 26630220, 536415300, 10805642100, 217666494900, 4384657426500, 88323978892500, 1779188631250500, 35839769985112500, 721952272492222500, 14542924237284172500, 292951012163242162500 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 2 of A183819.
LINKS
FORMULA
Empirical: a(n) = 15*a(n-1) + 120*a(n-2) - 330*a(n-3).
Empirical g.f.: 2*x*(4 + 21*x - 67*x^2) / (1 - 15*x - 120*x^2 + 330*x^3). - Colin Barker, Apr 04 2018
EXAMPLE
Some solutions with upper left block zero for 5 X 3:
0 0 0 0 0 0 0 0 1 0 0 2 0 0 1 0 0 0 0 0 2
0 0 2 0 0 1 0 0 1 0 0 1 0 0 0 0 0 2 0 0 2
0 1 0 0 2 0 0 1 2 2 1 1 0 2 2 1 1 0 0 2 2
2 2 1 1 2 0 1 1 2 2 1 2 0 2 2 0 2 1 0 2 1
1 0 1 1 0 2 1 1 1 0 2 1 0 1 0 1 2 2 2 0 0
CROSSREFS
Cf. A183819.
Sequence in context: A065116 A240410 A061250 * A222274 A061711 A316998
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 07 2011
STATUS
approved

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Last modified April 19 10:31 EDT 2024. Contains 371791 sequences. (Running on oeis4.)