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A203929
Number of (n+1) X 4 0..5 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements.
1
47916, 2543436, 140120856, 7748585676, 428652828396, 23714024087016, 1311917257647036, 72578467770478956, 4015218299044750776, 222131694756911277996, 12288868539361015411116, 679850257967547125048136
OFFSET
1,1
COMMENTS
Column 3 of A203934.
LINKS
FORMULA
Empirical: a(n) = 61*a(n-1) - 315*a(n-2) + 50*a(n-3).
Empirical g.f.: 36*x*(1331 - 10540*x + 1800*x^2) / (1 - 61*x + 315*x^2 - 50*x^3). - Colin Barker, Jun 05 2018
EXAMPLE
Some solutions for n=4:
..4..5..5..1....2..2..4..5....1..5..4..4....5..0..1..5....0..5..5..0
..2..4..5..5....2..5..2..4....4..1..5..4....2..5..0..1....0..0..5..5
..2..2..4..5....3..2..5..2....1..2..1..5....4..2..5..0....4..0..0..5
..1..2..2..4....3..3..2..3....0..1..5..4....5..4..2..5....4..4..0..0
..1..1..2..2....5..3..3..0....2..0..1..5....0..5..4..2....1..4..4..0
CROSSREFS
Cf. A203934.
Sequence in context: A190927 A251455 A204402 * A234172 A236716 A234297
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 08 2012
STATUS
approved